RFE: Lint pull request files

[zbeekman]

Is your feature request related to a problem? Please describe.

When not linting all files, EC lint failures in older commits will pass if the failing file is not touched in more recent commits. This is definitely not good for pull requests.

Describe the solution you'd like

When not linting all files, pull requests should trigger actions to lint all touched files in the pull request. This is probably a simple matter of adding an option for watching a pull-request event.

Describe alternatives you've considered

The only real alternative is to lint everything