Fleshed out the "Optimize Mesh" options found in the mesh import UI
Gave a checkbox to every vertex attribute that can be compressed
Surfaced option to enable/disable Octahedral compression for
normal/tangent vectors
Also surfaces the vertex position compression option which previously
inaccessible because the defaults did not compress vertex positions
Supports all current importers (obj, fbx, collada, gltf)
Create GLTFSkeleton at the same time we create GLTFNode objects.
Create GLTFSkin at the same time we export MeshInstance3D
Fixes export of blend shape arrays for meshes with multiple surfaces.
Fixes array indexing issues in export of glTF morph target animations.
Converts BoneAttachment3D nodes during normal node creation: this avoids
special cases during mesh export, and especially exporting skeletons or meshes
which are children of BoneAttachment3D.
Co-authored-by: K. S. Ernest (iFire) Lee <ernest.lee@chibifire.com>
