Blender Git Loki

Fix T84389: RGB Curves node shows "tone" option outside of compositor

Since the introduction in rB4de7c0c3105a, the option is only used in the
compositor, it has no effect elsewhere [texture nodes, shader nodes].

Now only show the option for the compositor.

Maniphest Tasks: T84389

Differential Revision: https://developer.blender.org/D10005