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>

homeassistant/generated/config_flows.py

@@ -692,6 +692,7 @@ FLOWS = {
         "weatherflow",
         "weatherflow_cloud",
         "weatherkit",
+        "webdav",
         "webmin",
         "webostv",
         "weheat",