Split up automatic build process

[IllustrisJack]

I feel like that it should be two different gh action workflows, one for engine and one for script changes.

If there are only script changes pushed we could technically reuse the latest engine/bin artifacts right?

[dgavedissian]

Is it causing any particular problems right now? It would be quite difficult to share artifacts between builds I think, and it's quite nice that every PR generates a zip file that technically can be shared with anyone without any further changes.

[IllustrisJack]

it doesn´t produce "problems" - but for every script push technically you´ll have to wait 5-10min to get a release even though that wouldn´t be necessary.

I think https://github.com/actions/cache would be an option - low prio.