SL-19014 Sanitize the override data sent for faces without GLTF materials

Attempt to simplify and avoid use of GL_UNSIGNED_INT_8_8_8_8_REV where not needed

SL-18869 Followup -- leverage "small commands" and time slicing to get rid of frame stalls on main thread without the need for multithreaded GL

SL-18869, SL-18772  Overhaul VBO management, restore occlusion culling, intel compatibility pass, etc

Not supposed to happen, yet somehow did

Sl 18820: Build floater should preserve GLTF transforms when changing the PBR material

SL-18869 Touch up -- Prune "post_pos" from shadow shaders that don't need it and fix non-standard gl_Position z values

SL-18869 Optimizations -- Revive "Frame Profile" and GL_DEPTH_CLAMP.  Remove usage of gl_FragDepth from shadow shaders.

SL-18820: Fix applying material clearing transform overrides. Loosen some asserts to allow non-default transform overrides.

SL-18869 Optimizations -- Quiet command buffer -- VBO cache for UI et al and remove many unneeded VBO binds.

SL-18869 Optimizations -- LLVertexBuffer overhaul and shuffle of shadow map rendering to a place where the main camera has taken a stab at object updates for this frame before shadow map rendering has at them.