Add missing config key for no_url_available when generating new oauth2
config entry based integrations.  This was found in issue #42423 where
the nest integration was missing a string when a user had a misconfiguration.

* Add MQTT integration discovery

* Add script/hassfest/mqtt.py

* Unsubscribe if config entry exists

* Add homeassistant/generated/mqtt.py

* Fix bad loop

* Improve tests

* Improve tests

* Apply suggestions from code review

Co-authored-by: Fabian Affolter <mail@fabian-affolter.ch>

* Prevent initiating multiple config flows

Co-authored-by: Fabian Affolter <mail@fabian-affolter.ch>

Co-authored-by: Paulus Schoutsen <paulus@home-assistant.io>

Co-authored-by: Franck Nijhof <git@frenck.dev>

Co-authored-by: Paulus Schoutsen <paulus@home-assistant.io>

Co-authored-by: Paulus Schoutsen <paulus@home-assistant.io>

* Check requirements don't conflict stdlib

* Use regex

Allow disabling integrations in manifest, block uuid package being installed and disable ezviz (#38444)

Co-authored-by: Paulus Schoutsen <balloob@gmail.com>
Co-authored-by: Martin Hjelmare <marhje52@gmail.com>
Co-authored-by: Franck Nijhof <git@frenck.dev>

Co-authored-by: Paulus Schoutsen <balloob@gmail.com>
Co-authored-by: Martin Hjelmare <marhje52@gmail.com>
Co-authored-by: Franck Nijhof <git@frenck.dev>

Shebang takes only one arg, regression in
f6540e30

* Reference constraint files from requirement files

* Update azure-pipelines-wheels.yml

Co-authored-by: Pascal Vizeli <pvizeli@syshack.ch>