Preserve image mimeType when converting from GLB to GLTF

The image mimeType field is mandatory when referencing a buffer (which is typical in GLB format) but optional when referencing files with well known extensions. It is stripped from the exported GLTF file, but it would be nice to have as a way to reduce ambiguity and for human readability. This is especially useful for files with extensions that use exotic image formats, which can lead to the exporter using the default .bin extension.

[emackey]

I’ll get a new version of gltf-vscode published in the coming days that uses the updated converter.

[rawnsley]

Thanks for the super quick turnaround.