[Code coverage] Introduce new GH actions workflow to compute coverage for JS/TS files

[achyuthajoy]

Introduce a new GitHub workflow to compute code coverage for changed files on a Pull Request

Acceptance criteria

• Introduce changes for WooPayments client (v1 & v2)
• The workflow should run only against pull requests with JS/TS files changed
• The workflow should compute:
  • Code coverage of base branch for the JS files changed on the pull request
  • Code coverage for the JS files changed on the pull request
• The coverage should be computed in Clover XML format
• The workflow should parse & compare the Clover XML files and added to the PR as comment (Refer to the 1CmafewXa4SdOSl1k7FIdNcOuBaqmVdNj9Jf4k98NRus-gdoc for available options)
• The workflow shouldn't prevent developers from merging the PR