fix(@angular/build): json and json-summary as vitest coverage reporters

[cexbrayat]

PR Checklist

Please check to confirm your PR fulfills the following requirements:

• The commit message follows our guidelines: https://github.com/angular/angular-cli/blob/main/CONTRIBUTING.md#-commit-message-guidelines
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

• Bugfix
• Feature
• Code style update (formatting, local variables)
• Refactoring (no functional changes, no api changes)
• Build related changes
• CI related changes
• Documentation content changes
• Other... Please describe:

What is the new behavior?

They can be quite handy for analysis tools.

See https://github.com/vitest-dev/vitest/blob/93f3200e452874ed4e2d018718bbbde7ebd28590/test/coverage-test/test/configuration-options.test-d.ts#L152 for all the current valid options

Does this PR introduce a breaking change?

• Yes
• No

Other information

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