Why

A user reported problems with UI tests. The originally used 'barichello/godot-ci' image was run in headless mode and caused the UI tests to fail.

What

Complete rewrite of all WF, direct download and use of the Godot versions instead of the docker image.
Drastic runtime reduction by caching the Godot binaries.
Conversion of existing WF to reusable WF running over ci-pr and dev-pr.
reworked on GdUnitSceneRunnerInputEventTest to stablise flaky tests according to global_mouse position was not correct set