GLTF Mesh Import: Root prim is random upon upload

[AtlasLinden]

Environment

Second Life Project Gltf Mesh Import 7.1.14.15830455952 (64bit)

Description

The root prim on uploaded GLTF models is selected randomly rather than using a defined root that is given in a 3D modeling app such as Blender.
The below image is a collection of the same uploaded model that each use a different root prim.

In Blender, this model has its root prim set as the right object of the wing (highlighted in yellow rather than orange).

See also the same issue for collada: https://github.com/secondlife/jira-archive-internal/issues/66897

Reproduction steps

Upload the same model multiple times and verify the objects root prim.
The model used in this issue (provided by aiaustin) can be found here: #4109 (comment)

[canny]

This issue has been linked to a Canny post: Random root object assignment upon upload of multi-object DAE file 🎉

[aiaustin]

Its quite tricky (impossible in general?) to get a consistent naming of a "root" mesh/prim for the glTF exports from Blender as the exporter may not simply use the last selected mesh part as a root and there are multiple possible Blender section methods. Also, since glTf transformatio and simlification tools are likely to be necessary (e.g. glf.report and glb.babylonpress,.com) these may join/weld parts and use unpredicatable part naming.