feature: Simultaneous multiple artifact upload to model registry model versions

Merge request: !165274 (merged)

feature: Simultaneous artifact upload to model registry model versions

Context

Upload artifacts to an existing machine learnin... (#456446 - closed) introduced an artifact uploader for existing model versions.

Assumed problem

• Users should be able to select multiple files and upload at the same time
• Gitlabdotcom performance should be considered, so this feature should be doable whenever we have direct uploads to cloud provided signed URL after Allow users to configure third party storage (#412731)

Proposal

• Allow multiple selection
• Upload each file concurrently