[Misc] Refactor VLM common generation tests to support audio inputs and mix-modality tests

[Isotr0py]

• After [CI/Build] Reorganize models tests #17459, we should add mixed modality tests for omni models, since we no longer group tests by modality.
• This PR refactors the generation/test_common.py tests to support audio inputs for mixed modality tests.
• This PR also adds Image-Audio mixed-modality tests for Qwen2.5-omni

[github-actions]

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[DarkLight1337]

Let's wait for transformers 4.52.0 so this test is actually being run in CI

[mergify]

This pull request has merge conflicts that must be resolved before it can be
merged. Please rebase the PR, @Isotr0py.

https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/working-with-forks/syncing-a-fork

[github-actions]

This pull request has been automatically marked as stale because it has not had any activity within 90 days. It will be automatically closed if no further activity occurs within 30 days. Leave a comment if you feel this pull request should remain open. Thank you!