Cleanup: move public doc-strings into headers for 'gpu'

Ref T92709

source/blender/gpu/opengl/gl_state.cc

@@ -84,7 +84,6 @@ void GLStateManager::apply_state()
   active_fb->apply_state();
 };
 
-/* Will set all the states regardless of the current ones. */
 void GLStateManager::force_state()
 {
   /* Little exception for clip distances since they need to keep the old count correct. */
@@ -482,7 +481,6 @@ void GLStateManager::texture_bind(Texture *tex_, eGPUSamplerState sampler_type,
   dirty_texture_binds_ |= 1ULL << unit;
 }
 
-/* Bind the texture to slot 0 for editing purpose. Used by legacy pipeline. */
 void GLStateManager::texture_bind_temp(GLTexture *tex)
 {
   glActiveTexture(GL_TEXTURE0);