Migrate coverage from v8 to c8

[aentwist]

Clear and concise description of the problem

The latest stable version of vitest 0.34.6 uses v8 for that flavor of coverage. However, from v8,

This package has been deprecated

Author message:
This tool was built when c8 package wasn't ready to be used, c8 has now more functionality and works better that this module. So you should really use c8.

Suggested solution

Go back to c8

Alternative

Suggest to install c8, but use c8 or v8 - whichever one is available (allow choice via manual installation)

Edit: after reading more I guess this is literally 2x the effort to maintain so it isn't possible

Additional context

Pull request that includes the motivation for moving from c8 to v8 #3339

Validations

• Follow our Code of Conduct
• Read the Contributing Guidelines.
• Read the docs.
• Check that there isn't already an issue that request the same feature to avoid creating a duplicate.

[aentwist]

Workaround: pin vitest version to 0.31

[sheremet-va]

Vitest never used that package. To use v8 coverage, install @vitest/coverage-v8. v8 is the name of the engine, not the tool. Vitest uses native inspector to collect native coverage in that case.