feat: add LLF support to effect and waters shaders

[doodlum]

• Effect shaders should work 1:1 compared to vanilla
• Water shaders should work differently, since they have access to high quality normal maps. I found that vanilla water specularity is way too bright, so I've darkened it to match the new lighting on non-strict portal lights. Might improve performance vs vanilla because it reduces draw calls on water.
• VR is detected so that these flatrim-specific changes should not affect it.
• Some shadercache code has been refactored to be accessible elsewhere.

[alandtse]

Do you need to bump the version too? Or do you want to do it separately because of other prs?

[doodlum]

Do you need to bump the version too? Or do you want to do it separately because of other prs?

I'll deal with it when checking what features changed since the last set of releases.