Add NextDNS integration (#74150)

* Initial commit

* Update manifest

* Add first test

* Simplify init

* More tests

* Update tests

* More tests

* More tests

* Add tests for sensor platform

* More tests for sensor platform

* Add tests for system_health

* Fix typo

* Improve test coverage

* Improve test coverage

* Add tests for diagnostics

* Add comment

* Run hassfest

* Fix typo

* Run gen_requirements_all

* Fix tests

* Change key name in diagnostics

* Remove diagnostics and system_health platforms

* Bump library

homeassistant/generated/config_flows.py

@@ -235,6 +235,7 @@ FLOWS = {
         "netatmo",
         "netgear",
         "nexia",
+        "nextdns",
         "nfandroidtv",
         "nightscout",
         "nina",