Feature Description

When opening a pull request that changes files to one plugin, only the unit tests for that plugin should run. This will greatly speed up our workflows (and reduce wasted compute), especially now that code coverage is being performed. That said, would it be problematic if PRs didn't include coverage reports for all plugins?

Note that a PR that modifies Optimization Detective should also cause the tests for Embed Optimizer and Image Prioritizer to also run, since they are dependent on that plugin.

Naturally, all tests would run for all plugins for commits added to trunk.

This has been suggested before by @thelovekesh, but I don't remember where.