Allow passing path to executable and export templates tpz instead of url

[Atlinx]

I'm using a custom build of Godot, and the export templates .tpz is stored inside of a zip file, so I cannot just pass it into godot_export_templates_download_url argument. It would be nice if we could manually pass in the file path to the export templates and the godot executable, in case we have to do some processing before hand.

I'd image it could look something like this:

      - name: Export Game
        id: export
        uses: firebelly/godot-export@v4.2.0
        with:
          godot_executable_path: $HOME/downloads/godot.x11.opt.tools
          godot_export_templates_download_path: $HOME/downloads/export_templates.tpz

[firebelley]

I agree, this would definitely be helpful! In the meantime, is it feasible for you to host your custom build and export templates somewhere where it can be downloaded in the action? Or are you building the engine in the same workflow?

[Atlinx]

The custom build is done via a GitHub Actions workflow, so I'm changing it to release the .tpz artifact as a .tpz instead of wrapping it in a zip.