Fixes #3494

Changes:

I have verified that this pull request:

I've made the following changes to support GLTF, GLB, and FBX file uploads:
Added 'gltf', 'glb', and 'fbx' to the fileExtensionsArray
Added the corresponding MIME types to the mimeTypes string:
model/gltf-binary for GLB files
model/gltf+json for GLTF files
application/x-fbx for FBX files
These changes will allow users to upload GLTF, GLB, and FBX files through the file uploader. The files will be handled by the existing upload infrastructure, which includes:
File size validation (max 5MB per file)
S3 storage for larger files
Local storage for smaller text-based files
Proper MIME type handling

• has no linting errors (npm run lint)
• has no test errors (npm run test)
• is from a uniquely-named feature branch and is up to date with the develop branch.
• is descriptively named and links to an issue number, i.e. Fixes #123