lib-storage: Hide and rmdir \NoSelect leaf mailboxes with NO-NOSELECT If the leaf is successfully rmdir()ed, rmdir() also its parents. This doesn't work perfectly with if there are multiple levels of \NoSelect mailboxes. For example with "a/b/c" the listing will already have returned "a" and "a/b" before it reaches the "a/b/c" code, which will rmdir all of them, but it's a bit too late at that point. It's too much work to fix though, and the situation will be fixed on the next list anyway.

lib-storage: Don't list duplicate autocreated mailboxes' parents

lib-storage: Add mailbox-list-iter-private.h with autocreate context structs Needed for the following ACL change.