Removes AppVeyor and all Travis jobs but the iOS one, which hasn't been ported
to GitHub Actions yet (should be done soon).
Backports new style scripts from `master` branch too to do the same checks.
This was based on quarmin's initial configuration, we had compile issues with AppVeyor being super slow and GitHub actions will take less time and also manage a full rebuild in 30 minutes.
This adds cache handling and will work with MSVC and scons 4.0, it will build for every PR submitted to the Godot Engine, and also for the branches specified. I have tested the caching and it seems to be working.
I left the 'publish artefacts' disabled until we can request more storage from Microsoft, 5 GB is far to low for us and we would eat this limit very fast. (it is tested and works fine)
Co-authored-by: Rafał Mikrut <mikrutrafal54@gmail.com>
(cherry picked from commit 04592af5a4)
Keeping CONTRIBUTING.md at the root so that contributors actually find it.
Also changed the custom FUNDING.yml link to point to godotengine.org/donate,
which also links to PayPal and other options.
