POC: Create and persist "magiclink" shares #2516

Description

Create a POC implementation that allow creating and managing shares to email addresss not tied to an existing users. As described in #2513.
Accessing the shared resources is not is scope for this POC.

Not is scope

• authentication of "magiclinks"
• sending mails

Acceptance Criteria

• feature branch
• graph API permission endpoints allow sharing with email addresses not tied to an exiting users
• usershare-manager persists the shares
• grants are persisted on storage