Error Handling and State Management for Graveler Entities [Discovery]

[itaidavid]

Following #3591 and #3646 - we recognized the need for a better error handling mechanizm within graveler. #3646 handles the Repository section of graveler but similar discovery and implementation should apply to (at least) Branch entities and possibly other entities too

This is a Discovery & Design task

DoD A document with all problematic Branch related flows, that need to be better handeld over KV, with a proposed solution