Detect and persist the personal namespace

appinfo/info.xml

lib/Db/MailAccount.php

lib/IMAP/MailboxSync.php

lib/Migration/Version1050Date20200831124954.php

src/store/actions.js

src/store/mutations.js

src/tests/unit/store/actions.spec.js

src/tests/unit/store/mutations.spec.js

tests/Integration/Db/MailAccountTest.php

tests/Unit/IMAP/MailboxSyncTest.php