[UIKit] Correct nullability attributes for parts of UIKit

[rpendleton]

These changes correct some of the nullability attributes for the UIKit bindings. Although UIKit has several hundred lines of xtro-sharpie ignores related to nullability, this PR only fixes a few of them.

I wasn't sure where to draw the line, but in the end, I essentially fixed most of UIViewController and all of UITableView and UICollectionView. These classes were the ones that led to the most // ReSharper disable comments being added in my team's codebase, and/or that led to crashes being introduced by devs following ReSharper's suggestions to remove "unnecessary" null-checks.

These changes were largely based on the instructions given by @spouliot in #6154. However, I noticed the xtro-sharpie ignore files have been duplicated in the api-annotations-dotnet directory since then, so I updated the .ignore and .todo files in that directory as well.

If the process has changed since that comment was written, I can make any additional changes that are needed.

[rolfbjarne]

/azp run

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).

[rolfbjarne]

This looks great! Thanks!

[rolfbjarne]

These changes were largely based on the instructions given by @spouliot in #6154. However, I noticed the xtro-sharpie ignore files have been duplicated in the api-annotations-dotnet directory since then, so I updated the .ignore and .todo files in that directory as well.

That's correct, since spouliot wrote those instructions, we have a different set if xtro files for the .NET assemblies, and you'll have to remove the same entries from those files as well. I've updated the instructions in that comment accordingly.

[chamons]

Looks like some of the CI choked on the build:

##[error]We stopped hearing from agent VSM-XAM-35.BigSur.arm64. Verify the agent machine is running and has a healthy network connection. Anything that terminates an agent process, starves it for CPU, or blocks its network access can cause this error. For more information, see: https://go.microsoft.com/fwlink/?linkid=846610

@mandel-macaque - Can this go in? I think that's signing stuff and this is fine, but I'm out of the loop here.

[mandel-macaque]

Results seem ok, but I have merge with main and will re-trigger a build.

[mandel-macaque]

/azp run

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).

[rolfbjarne]

/azp run

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).

[vs-mobiletools-engineering-service2]

📚 [PR Build] Artifacts 📚

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• Microsoft.iOS.Bundle.15.4.166-ci.pr.gh15200.pkg
• Microsoft.iOS.Ref.15.4.166-ci.pr.gh15200.nupkg
• Microsoft.iOS.Runtime.ios-arm.15.4.166-ci.pr.gh15200.nupkg
• Microsoft.iOS.Runtime.ios-arm64.15.4.166-ci.pr.gh15200.nupkg
• Microsoft.iOS.Runtime.iossimulator-arm64.15.4.166-ci.pr.gh15200.nupkg
• Microsoft.iOS.Runtime.iossimulator-x64.15.4.166-ci.pr.gh15200.nupkg
• Microsoft.iOS.Runtime.iossimulator-x86.15.4.166-ci.pr.gh15200.nupkg
• Microsoft.iOS.Sdk.15.4.166-ci.pr.gh15200.nupkg
• Microsoft.iOS.Templates.15.4.166-ci.pr.gh15200.nupkg
• Microsoft.iOS.Windows.Sdk.15.4.166-ci.pr.gh15200.nupkg
• Microsoft.MacCatalyst.Bundle.15.4.166-ci.pr.gh15200.pkg
• Microsoft.MacCatalyst.Ref.15.4.166-ci.pr.gh15200.nupkg
• Microsoft.MacCatalyst.Runtime.maccatalyst-arm64.15.4.166-ci.pr.gh15200.nupkg
• Microsoft.MacCatalyst.Runtime.maccatalyst-x64.15.4.166-ci.pr.gh15200.nupkg
• Microsoft.MacCatalyst.Sdk.15.4.166-ci.pr.gh15200.nupkg
• Microsoft.MacCatalyst.Templates.15.4.166-ci.pr.gh15200.nupkg
• Microsoft.macOS.Bundle.12.3.166-ci.pr.gh15200.pkg
• Microsoft.macOS.Ref.12.3.166-ci.pr.gh15200.nupkg
• Microsoft.macOS.Runtime.osx-arm64.12.3.166-ci.pr.gh15200.nupkg
• Microsoft.macOS.Runtime.osx-x64.12.3.166-ci.pr.gh15200.nupkg
• Microsoft.macOS.Sdk.12.3.166-ci.pr.gh15200.nupkg
• Microsoft.macOS.Templates.12.3.166-ci.pr.gh15200.nupkg
• Microsoft.NET.Sdk.iOS.Manifest-6.0.300.15.4.166-ci.pr.gh15200.nupkg
• Microsoft.NET.Sdk.MacCatalyst.Manifest-6.0.300.15.4.166-ci.pr.gh15200.nupkg
• Microsoft.NET.Sdk.macOS.Manifest-6.0.300.12.3.166-ci.pr.gh15200.nupkg
• Microsoft.NET.Sdk.tvOS.Manifest-6.0.300.15.4.166-ci.pr.gh15200.nupkg
• Microsoft.NET.Workload.iOS.15.4.166-ci.pr.gh15200.msi
• Microsoft.tvOS.Bundle.15.4.166-ci.pr.gh15200.pkg
• Microsoft.tvOS.Ref.15.4.166-ci.pr.gh15200.nupkg
• Microsoft.tvOS.Runtime.tvos-arm64.15.4.166-ci.pr.gh15200.nupkg
• Microsoft.tvOS.Runtime.tvossimulator-arm64.15.4.166-ci.pr.gh15200.nupkg
• Microsoft.tvOS.Runtime.tvossimulator-x64.15.4.166-ci.pr.gh15200.nupkg
• Microsoft.tvOS.Sdk.15.4.166-ci.pr.gh15200.nupkg
• Microsoft.tvOS.Templates.15.4.166-ci.pr.gh15200.nupkg
• xamarin.ios-15.11.0.354.pkg
• xamarin.mac-8.11.0.354.pkg

Pipeline on Agent XAMBOT-1107.Monterey'
Hash: a8370e9297f7ee7dc7643c4d01275dd4d6159a26

[vs-mobiletools-engineering-service2]

❌ [PR Build] Tests on macOS Mac Catalina (10.15) failed ❌

Failed tests are:

• monotouch-test

Pipeline on Agent
Hash: a8370e9297f7ee7dc7643c4d01275dd4d6159a26

[vs-mobiletools-engineering-service2]

📋 [PR Build] API Diff 📋

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API diff: vsdrops gist

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• iOS vsdrops gist
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• watchOS vsdrops gist

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• dotnet-iOS vsdrops gist
• dotnet-macOS vsdrops gist
• dotnet-tvOS vsdrops gist
• dotnet-MacCatalyst vsdrops gist

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• dotnet-legacy-iOS vsdrops gist
• dotnet-legacy-macOS vsdrops gist
• dotnet-legacy-tvOS vsdrops gist

iOS vs Mac Catalyst (.NET)

• dotnet-macCatiOS vsdrops gist

API diff (vs stable)

✅ API Diff from stable

API diff: vsdrops gist

Xamarin

• iOS vsdrops gist
• macOS vsdrops gist
• tvOS vsdrops gist
• watchOS vsdrops gist

.NET

• dotnet-iOS vsdrops gist
• dotnet-macOS vsdrops gist
• dotnet-tvOS vsdrops gist
• dotnet-MacCatalyst vsdrops gist

Xamarin vs .NET

• dotnet-legacy-iOS vsdrops gist
• dotnet-legacy-macOS vsdrops gist
• dotnet-legacy-tvOS vsdrops gist

iOS vs Mac Catalyst (.NET)

• dotnet-macCatiOS vsdrops gist

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Pipeline on Agent XAMBOT-1109.Monterey
Hash: a8370e9297f7ee7dc7643c4d01275dd4d6159a26

[vs-mobiletools-engineering-service2]

💻 [PR Build] Tests on macOS M1 - Mac Big Sur (11.5) passed 💻

✅ All tests on macOS M1 - Mac Big Sur (11.5) passed.

Pipeline on Agent
Hash: a8370e9297f7ee7dc7643c4d01275dd4d6159a26

[vs-mobiletools-engineering-service2]

✅ [CI Build] Tests passed on VSTS: simulator tests iOS. ✅

Tests passed on VSTS: simulator tests iOS.

• Azure DevOps
• Html Report (VSDrops) Download

🎉 All 148 tests passed 🎉

Pipeline on Agent XAMBOT-1030.Monterey'
Merge a8370e9 into 6c5a95b

[rolfbjarne]

Great work! Thanks a lot!