JAMES-3945 IMAP & JMAP right management for sub addressing

[florentos17]

refs:

• wikipédia for Sub-addressing
• RFC5233 for subaddress extension
• the jira ticket

the first part of the work is done, now subaddressing works on the backend side, CF the first github issue and the associated PR

right positioning using IMAP, eg setting the p right for a specific folder for either no one or anyone, is also done, CF this PR

remains to be done: right positioning using JMAP. speaking to @chibenwa, we agreed to wait for front-end support before carrying on with that.