Co-authored-by: Nat Goodspeed <nat@lindenlab.com>

Fix some folders not being requested unless already cached.
Fix materials folder not being requested by materials picker.

Handle obscure upload failure case - floater was waiting for a texture upload indefinetely.
Unblock floater if upload fails.

SL-18784 Refactor physics shape display to not require its own render target.  Remove "Hover Glow Objects" to free up a superfluous render target.

SL-18785 Fix for corrupt reflection probes on various preference changes.  Add UI for Screen Space Reflections.

SL-18692 Fix for fullbright alpha not clipping against water plane (also fixes ultraspace particles).

Due to udp texture fetching no longer being present

Show a tooltip on drag&drop

SL-18154 WIP -- CPU sampling (AMD uProf) profile guided optimizations to reduce CPU usage of background threads.

Originally a fix for MAINT-4773/SL-5842 (transparent alpha being white). Reverting due to a critical flaw of the fix replacing material (sometimes server side included). And ignoring user and script input in some cases that makes scripts misbehave.

Viewer should Not modify existing content of own volition.

SL-18682 WIP -- Clear BOOST_SELECTED as needed.  GL 3.2 compatibility pass.  Fix for stack underflow when reflection probes disabled.