Mqtt support config_entry unload (#70149)
* squashed commits for rebase
* Flake
* Fix reloading issue manual legacy items
* Improve ACS sync for unsubscribe at disconnect
* Processed review comments
* Update homeassistant/components/mqtt/client.py
Co-authored-by: Erik Montnemery <erik@montnemery.com>
* No need to await entry setup
* Remove complication is_connected
* Update homeassistant/components/mqtt/__init__.py
Co-authored-by: Erik Montnemery <erik@montnemery.com>