Undelete: deleted accounts are kept for their period, hold their addresses, and are restored or destroyed through inbuxa:DeletedAccount (UD-15 to UD-17a)

With archiveDeletedAccountsFor set, a destroyed account's record is kept in
the fork subspace with its id, its DestroyAccount task is due at the end of
the period, and its shares are suspended both ways. Its addresses can't be
taken by new accounts, aliases, lists or masks. inbuxa:DeletedAccount/get
lists kept accounts to server and tenant administrators; /set restores one
with a new password (same id, task cancelled, shares reinstated) or destroys
it now. The destroy task also clears undelete's own records.
Acceptance test 14; test 16 written as the ignored undelete_compat.

crates/jmap-proto/src/object/mod.rs

@@ -19,6 +19,7 @@ pub mod contact;
 pub mod email;
 pub mod email_submission;
 pub mod fastmail_masked_email; // inbuxa: masked email
+pub mod inbuxa_deleted_account; // inbuxa: undelete
 pub mod file_node;
 pub mod identity;
 pub mod mailbox;