Make JSON schema generator check action required

With #211 we have a generated json schema in place to support certain IDE integrations for model editing, and #216 adds a github action to ensure that schema remains up to date.

Ideally that action would be required on every PR, but because any action with a "path" conditional will always be marked pending unless the path condition is met those actions will never be considered successful. This means we can't use them in branch protection.

The work-around is to make the workflow run two jobs on every PR, one of which uses something like the [dorny/paths-filter](https://github.com/dorny/paths-filter) action and the other of which only runs if the path condition check passes. This will let us add branch protection.