Texture compression UI is confusing

[slimbuck]

The inspector UI which deals with texture compression can be quite confusing. It's not always obvious what the current state is and how to update textures.

For example, to remove a compressed texture it is necessary to disable the compression toggle and then recompress.

Users have struggled with this too, see https://forum.playcanvas.com/t/solved-not-able-to-use-texture-compression-feature/26983.