DIAGNOSTIC (do not merge): assembly bind logging for net472 importer tests

[wasabii]

Draft, not for merge. Temporary instrumentation to identify one unknown, then revert.

Why

IKVM.Tools.Importer.Tests on net472 fails every row on main with:

Could not load file or assembly 'System.Collections.Immutable, Version=10.0.0.0' ...
 ---> Could not load file or assembly 'System.Collections.Immutable, Version=8.0.0.0' ...
   at IKVM.Tools.Importer.ImportOptions..ctor()

The generated IKVM.Tools.Importer.Tests.exe.config contains:

<assemblyIdentity name="System.Collections.Immutable" publicKeyToken="b03f5f7f11d50a3a" culture="neutral" />
<bindingRedirect oldVersion="0.0.0.0-8.0.0.0" newVersion="8.0.0.0" />

A 10.0.0.0 reference falls outside 0.0.0.0-8.0.0.0, so the redirect never applies and the loader binds 10.0.0.0 literally against a file that really is 8.0.0.0 (FileVersion 8.0.23.53103). That much is confirmed from the run 29223646609 artifact.

The unknown

Nothing I can enumerate explains where the 10.0.0.0 reference comes from. Checked and ruled out:

• all 68 assemblies in tests/IKVM.Tools.Importer.Tests/net472/ — highest is 8.0.0.0 (IKVM.CoreLib, IKVM.Tools.Importer, System.Reflection.Metadata); the rest ask for 1.2.3.0–6.0.0.0
• IKVM.Runtime.dll / IKVM.Java.dll — no reference to it at all
• SDK 10.0.302 TestPlatform / TestHost / diagnostics assemblies — none reference version ≥ 9

The failing run logs WRN: Assembly binding logging is turned OFF., so this turns it on and prints any bind-failure log naming the assembly. That names the requester directly instead of guessing.

Changes

Two steps in the test job, both gated to Windows + IKVM.Tools.Importer.Tests:

• Enable Assembly Binding Log — sets HKLM\SOFTWARE\Microsoft\Fusion LogFailures/EnableLog with a LogPath under the work dir
• Dump Assembly Binding Log — if: always(), strips HTML and prints matching failure logs to the job output

Once the requester is known, this is reverted and the real fix goes in separately.

Related: this is one of the failures blocking #725, whose own change is correct and adds no failures of its own.