feat: Support MOCHA_GREP/MOCHA_INVERT envvars

[TamiTakamiya]

This PR for allowing Mocha's grep/invert options through environment variables MOCHA_GREP and MOCHA_INVERT. Following examples show how it can be used:

# Run the test case whose name is "ExtensionsView"
MOCHA_GREP="ExtensionsView" npm run test

# Run the test cases whose name is NOT "ExtensionsView"
 MOCHA_GREP="ExtensionsView" MOCHA_INVERT=true npm run test

Before submitting your PR, please review the following checklist:

• [X] CONSIDER adding a new test if your PR resolves an issue.
  • I did manually tested them. I thought it would be enough as the changes are simple enough.
• [X] DO keep pull requests small so they can be easily reviewed.
• [X] DO make sure tests pass.
• [X] DO make sure any public APIs changes are documented.
• [X] DO make sure not to introduce any compiler warnings.

Before merging the PR:

• [ ] CHECK continuous integration of main branch is green.
• [ ] CHECK pull request check job is green.
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[sonarcloud[bot]]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
No data about Coverage
0.0% Duplication on New Code

See analysis details on SonarCloud