[MIG] mail: migrate remaining code in old API

addons/mail/controllers/main.py

addons/mail/models/ir_autovacuum.py

addons/mail/models/mail_template.py

addons/mail/models/mail_thread.py

addons/mail/models/update.py

addons/mail/tests/common.py

addons/mail/tests/test_mail_channel.py

addons/mail/tests/test_message_track.py

addons/mass_mailing/models/mass_mailing.py