Add SNMP Walk for Network Device Discovery and Monitoring #5184

Is your feature request related to a problem? Please describe.
When monitoring network devices through SNMP, users may need to identify available OIDs and determine which metrics a device exposes. Manually specifying individual OIDs can make discovery and configuration time-consuming.

Tools such as Zabbix provide SNMP walk functionality to explore the OID tree exposed by a network device.

Describe the solution you'd like
Add an SNMP Walk capability to OneUptime that allows users to query a device's SNMP agent and discover available OIDs and their returned values.

The functionality should support:

SNMP v2c and SNMP v3, subject to the configured credentials and supported security options.

Walking an OID subtree or starting from a specified OID.

Displaying the returned OID, value, and data type.

Showing useful errors for authentication failures, timeouts, and unreachable devices.

Allowing users to identify relevant OIDs for subsequent monitor configuration.

Respecting device permissions, credential security, and polling limits.

Describe alternatives you've considered
Users should be able to explore a network device's available SNMP information directly in OneUptime instead of having to manually look up and configure every OID.

SNMP Walk should complement existing monitoring capabilities and help users build device-specific monitoring configurations more efficiently.