Add WebDAV backup agent (#137721)

* Add WebDAV backup agent

* Process code review

* Increase timeout for large uploads

* Make metadata file based

* Update IQS

* Grammar

* Move to aiowebdav2

* Update helper text

* Add decorator to handle backup errors

* Bump version

* Missed one

* Add unauth handling

* Apply suggestions from code review

Co-authored-by: Josef Zweck <josef@zweck.dev>

* Update homeassistant/components/webdav/__init__.py

* Update homeassistant/components/webdav/config_flow.py

* Remove timeout

Co-authored-by: Josef Zweck <josef@zweck.dev>

* remove unique_id

* Add tests

* Add missing tests

* Bump version

* Remove dropbox

* Process code review

* Bump version to relax pinned dependencies

* Process code review

* Add translatable exceptions

* Process code review

* Process code review

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Co-authored-by: Josef Zweck <josef@zweck.dev>

CODEOWNERS

@@ -1695,6 +1695,8 @@ build.json @home-assistant/supervisor
 /tests/components/weatherflow_cloud/ @jeeftor
 /homeassistant/components/weatherkit/ @tjhorner
 /tests/components/weatherkit/ @tjhorner
+/homeassistant/components/webdav/ @jpbede
+/tests/components/webdav/ @jpbede
 /homeassistant/components/webhook/ @home-assistant/core
 /tests/components/webhook/ @home-assistant/core
 /homeassistant/components/webmin/ @autinerd