fix(anta.tests): Added testcase to verify IP virtual router mac address

[MaheshGSLAB]

Description

Added testcase to verify IP virtual router mac address

"""
Verifies the IP virtual router MAC address.

Expected Results:
    * success: The test will pass if the IP virtual router MAC address matches the input.
    * failure: The test will fail if the IP virtual router MAC address does not match the input.

"""

Fixes #561

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)

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