feat(anta): Added the test case to verify the SNMP source interface for specified VRF

[vitthalmagadum]

Description

Verifies SNMP source-interface for a specified VRF.

Expected Results
----------------
* Success: The test will pass if the provided SNMP source-interface is configured in the specified VRF.
* Failure: The test will fail if the provided SNMP source-interface is NOT configured in the specified VRF.

Fixes #854

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my code
• I have run pre-commit for code linting and typing (pre-commit run)
• I have made corresponding changes to the documentation
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes (tox -e testenv)

[sonarcloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
100.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud

[codspeed-hq]

CodSpeed Performance Report

Merging #870 will not alter performance

_{Comparing vitthalmagadum:issue_854 (b765061) with main (2541572)}

Summary

✅ 8 untouched benchmarks

[MaheshGSLAB]

Suggested change

	failures += f"Source interface '{interface}' is not configured.\n"
	failures += f"Source interface '{interface}' is not configured with vrf `{vrf}`.\n"

[MaheshGSLAB]

again what is expected and what actual interface received please mention that in failure message.

[github-actions]

This pull request has conflicts, please resolve those before we can evaluate the pull request.