RFE: Allow PE/Admins to rename or delete a namespace that has no artifacts in it

[thedoubl3j]

Recently we came across a namespace in Automation Hub that was misnamed to partners galaxy namespace. They preferred both to be the same as to provide docs/marketing parody across all of their messaging.

It would good if the PE role (or whichever is assigned to us) had the ability to change or delete a namespace that has no collections uploaded to it as to not burden the AH team with such requests.

cc: @newswangerd