mobile_app component (#21475)

* Initial pass of a mobile_app component

* Fully support encryption, validation for the webhook payloads, and other general improvements

* Return same format as original API calls

* Minor encryption fixes, logging improvements

* Migrate Owntracks to use the superior PyNaCl instead of libnacl, mark it as a requirement in mobile_app

* Add mobile_app to .coveragerc

* Dont manually b64decode on OT

* Initial requested changes

* Round two of fixes

* Initial mobile_app tests

* Dont allow making registration requests for same/existing device

* Test formatting fixes

* Add mobile_app to default_config

* Add some more keys allowed in registration payloads

* Add support for getting a single device, updating a device, getting all devices. Also change from /api/mobile_app/register to /api/mobile_app/devices

* Change device_id to fingerprint

* Next round of changes

* Add keyword args and pass context on all relevant calls

* Remove SingleDeviceView in favor of webhook type to update registration

* Only allow some properties to be updated on registrations, rename integration_data to app_data

* Add call service test, ensure events actually fire, only run the encryption tests if sodium is installed

* pylint

* Fix OwnTracks test

* Fix iteration of devices and remove device_for_webhook_id