[Feature] Warn about entity name collisions before submitting edits

[InfiniteStash]

Name collisions are frustrating since they only surface after the edit has been submitted and approved. We should check before submitting if an edit will result in a collision, and warn the user so they can reconsider, or clean up.

Examples: edit 06191bbc-8b24-4952-a0e7-b21aa50bebc1 edit f42af60b-71b7-457c-a662-19b1d0a28f2e