Ability to initiate Github checks _after_ "Merge When Ready" button is pressed

[sfc-gh-hduan]

Is your feature request related to a problem? Please describe.
We would like for the "Merge When Ready" button to initiate the Github checks, instead of using pre-existing results from the checks.

The reason for this is the checks could have been days stale when someone press the "Merge When Ready" button. We would like to have the most up-to-date status for the checks before the PR is merged.

Describe the solution you'd like
We would like for the checks to run after someone presses the "Merge When Ready" button and ignore preexisting results from the checks.

Describe alternatives you've considered
Internal solution applicable for our repo only: Disable the "Merge"/"Merge When Ready" button. We can either build a custom plugin or a way for developer to notify the intent to merge. We listen to the intent, run any validation/checks we want, and call an API to merge the code. This would result in a less optimal experience for Github users though.

Additional context
N/A