Add new flag: EXTRA_ARGS to support custom arguments

[dinhtungdu]

Description of the Change

This PR adds a new flag to support custom arguments. Originally, I hard-coded to generate a JSON file for job summary, but I think an extra argument is better because it lets users enable the JSON report generation only if they want to display the summary.

Closes #

Alternate Designs

Possible Drawbacks

Verification Process

See 10up/maps-block-apple#128 and https://github.com/10up/maps-block-apple/actions/runs/2326290393

Checklist:

• I have read the CONTRIBUTING document.
• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added tests to cover my change.
• All new and existing tests passed.

Changelog Entry

Added EXTRA_ARGS allows users to add custom arguments to the phpcs command.

Credits

Props @dinhtungdu