SL-19080: Restrict LLGLTFMaterial fields test to a single compiler target, as results can vary between compilers

SL-19080: Update GLTF Material asset upload to v1.1, with stricter GLTF compliance and removal of unsupported features

This commit adds the HBXX64 and HBXX128 classes for use as a drop-in
replacement for the slow LLMD5 hashing class, where speed matters and
backward compatibility (with standard hashing algorithms) and/or
cryptographic hashing qualities are not required.
It also replaces LLMD5 with HBXX* in a few existing hot (well, ok, just
"warm" for some) paths meeting the above requirements, while paving the way for
future use cases, such as in the DRTVWR-559 and sibling branches where the slow
LLMD5 is used (e.g. to hash materials and vertex buffer cache entries), and
could be use such a (way) faster algorithm with very significant benefits and
no negative impact.

Here is the comment I added in indra/llcommon/hbxx.h:

// HBXXH* classes are to be used where speed matters and cryptographic quality
// is not required (no "one-way" guarantee, though they are likely not worst in
// this respect than MD5 which got busted and is now considered too weak). The
// xxHash code they are built upon is vectorized and about 50 times faster than
// MD5. A 64 bits hash class is also provided for when 128 bits of entropy are
// not needed. The hashes collision rate is similar to MD5's.
// See https://github.com/Cyan4973/xxHash#readme for details.

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

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

And cleaned up dupplicate mScale code

Revert "SL-18523: When editing an object's material override, use the object's material override as a base, rather than its render material (pull request #1190)"

SL-18523: When editing an object's material override, use the object's material override as a base, rather than its render material

SL-18485: Render GLTF materials with extension KHR_texture_transform with approprate texture transforms

SL-18520 Use GLTF material.extras to pass flags for enabling overriding alpha mode and double sided to default

SL-18520 WIP - Use off-by-epsilon and special UUID identifier hacks to allow overriding to default values.

SL-18472 Fix for assert when increasing number of texture entries on existing primitive with overrides applied.

SL-18105 Add mechanism for applying overrides that were received before associated ViewerObject was ready to receive them.

SL-18411: Copy over LLGLTFMaterial changes (most notably various getters/setters and texture transform stub)

SL-18105 Hook up render pipe directly to LLTextureEntry::mGLTFMaterial and add LLViewerFetchedTextures to LLFetchedGLTFMaterial.  Lower reflection probe resolution to 128x128 per side.

LLGLTFMaterialList now decodes gltf json overrides from the server
and stores them in LLTextureEntry::mGLTFMaterialOverrides

WIP for SL-17697 live editing now computes diffs of changed material properties in tinygltf schema json

SL-18156 WIP -- Add NormalizedScale/NormalizedTranslation to mesh assets to recover mesh's original coordinate frame when generating tangents post download.