Rider Shader Variant feature doesn't work well and worsens the situation for .cginc files.

[Henry-Suen]

Shader keywords are only detected with "#pragma" in shader files.

But .cginc files function as a part of shader scripts that always don't need declarations of keywords. So those keyword branching parts are all grayed out, which makes editing inefficient. And they can't be enabled due to the incompetence of keyword detection.