Improve subscription management for JMAP

Why?

Subscription is held on a per mailbox basis and is used to show mailboxes or not in GUIs.

The issue is that JMAP do not show the full mailbox name (ie from the root) but only the right most folder name (excluding parents) combined with the id of the parent mailbox.

If a parent mailbox is hidden but a child is visible then the child will be hidden in JMAP.

So:

WHEN a mailbox is marked as visible
THEN all of its parents should be visible too

WHEN a mailbox is marked as hidden
THEN all of its children should be hidden too

What?

Write a mailbox listener, in mailbox/store, to propagate:

• subscription to parent mailboxes
• unsubscription to children mailboxes

Definition of Done

JMAP level integration tests.