Export multiple formats at the same time

The artist should have the possibility to select multiple formats under “Image and Data Output Export” and a seperate texture set for each format will be exported.

Justification

USD assets can have multiple material variants. Often times this is used to have 2 or more resolutions of the same textures.

Implementation Details

The format dropdown menu could be enhanced to select from various format templates and to add/edit them.

Thanks @gmc for your feature request.