This makes it easier to spot syntax errors when editing the
class reference. The schema is referenced locally so validation
can still work offline.
Each class XML's schema conformance is also checked on GitHub Actions.
Also added an easier way to load native GLSL shaders.
Extras:
Had to fix no-cache for subresources in resource loader, it was not properly working, making shaders not properly reload.
Note:
The precommit hooks are broken because they don't seem to support enums from one class being used in another.
Feel free to fix this after merging this PR.
