Enhancement/10145-vitest-migration

[benbowler]

Summary

Addresses issue:

• Migrate to Vitest #10145

Relevant technical choices

VITest base infra with 52% of tests fixed and passing.

An early note the current suite is running slower than Jest was. Although this could be todo with the number of failing tests still. In another hackathon I can get this ready for review.

PR Author Checklist

• My code is tested and passes existing unit tests.
• My code has an appropriate set of unit tests which all pass.
• My code is backward-compatible with WordPress 5.2 and PHP 7.4.
• My code follows the WordPress coding standards.
• My code has proper inline documentation.
• I have added a QA Brief on the issue linked above.
• I have signed the Contributor License Agreement (see https://cla.developers.google.com/).

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Code Reviewer Checklist

• Run the code.
• Ensure the acceptance criteria are satisfied.
• Reassess the implementation with the IB.
• Ensure no unrelated changes are included.
• Ensure CI checks pass.
• Check Storybook where applicable.
• Ensure there is a QA Brief.
• Ensure there are no unexpected significant changes to file sizes.

Merge Reviewer Checklist

• Ensure the PR has the correct target branch.
• Double-check that the PR is okay to be merged.
• Ensure the corresponding issue has a ZenHub release assigned.
• Add a changelog message to the issue.

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[benbowler]

If we get this to merge, create a follow up issue to do this work to improve overall performance.