Rename TextureUnitManager to not have the OpenGL

Just a cleanup to be more consistent with the old name convention.

Change-Id: Ic70bf2c9397b5b78727cf24a3f7d8c93984ee9c3
Rename texture unit manager to not have OpenGL in it

Be more consistent with the old OpenGL module

Change-Id: I36cae97009baa896e502b5d42280ae9c9554610c
Merge topic 'rename_texture_unit_manager' into master

b286b89e Rename texture unit manager to not have OpenGL in it
0140876d Rename TextureUnitManager to not have the OpenGL