Filter builds based on GHA webhook path filtering rules

[humitos]

AI attempt to implement https://github.com/readthedocs/meta/discussions/200#discussioncomment-15500050

Prompt:

We have the concept of "automation rules" that are executed when the versions are synced. Now, we want to create a new automation rule that is executed at GitHubAppWebhookHandler to decide whether or not a Build has to be triggered based on the files added/modified/deleted in the push webhook event

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I think this is pretty doable. I ask AI to implement it and it did the right thing, the overall is pretty good and doesn't seem to be super complex to adapt it to what we need.

We have a model called VersionAutomationRule that we may need to refactor/rename or similar because all the actions we currently have act over a Version and here we need just to block triggering a build. So, those actions make no sense here, but seems to be a small refactor anyway.

I'm opening this draft PR here as a way to share what I quickly found when using AI so we can continue our discussions.

[ericholscher]

This looks like a good start, but needs some additional work to actually work on PR builds, along with tests. But seems like a nice feature to have, and better UX than the 183 exit codes, since it doesn't even trigger the build in the first place.