[Ogre] Fix naming conflicts and double deletes
What does this MR do?
- Makes all resource names unique by prefixing the render service's name.
- Removes the depth buffer from the volume grid render target. It was unused and resulted in a double free crash.
- Adds some gl context switches were they could be missing.
- Fixes a crash when the ray entry compositor is deleted too soon.
- Updates the importance mask when setting the IDVR method.
- Removes the 'quit on escape' anti-feature.
How to test it?
- Make sure that OgreViewer isn't broken.