NC30: `webhook_listeners` app support

[bigcat88]

Not finished yet, because... I'm waiting for this to be finalized on the server.

The technology is very powerful, probably better than what happened with ExApp.

It can also be used as a Nextcloud client, but the client must have administrator access.

Some docs(and maybe article?) will come before NC30 release.

Reference: https://github.com/nextcloud/server/pull/46477

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 62.06897% with 33 lines in your changes missing coverage. Please review.

Project coverage is 94.17%. Comparing base (22cbea9) to head (d3e871a).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #272 +/- ## ========================================== - Coverage 94.69% 94.17% -0.52% ========================================== Files 47 48 +1 Lines 5405 5492 +87 ========================================== + Hits 5118 5172 +54 - Misses 287 320 +33 ``` | [Files](https://app.codecov.io/gh/cloud-py-api/nc_py_api/pull/272?dropdown=coverage&src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=cloud-py-api) | Coverage Δ | | |---|---|---| | [nc\_py\_api/nextcloud.py](https://app.codecov.io/gh/cloud-py-api/nc_py_api/pull/272?src=pr&el=tree&filepath=nc_py_api%2Fnextcloud.py&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=cloud-py-api#diff-bmNfcHlfYXBpL25leHRjbG91ZC5weQ==) | `96.22% <100.00%> (+0.08%)` | :arrow_up: | | [nc\_py\_api/webhooks.py](https://app.codecov.io/gh/cloud-py-api/nc_py_api/pull/272?src=pr&el=tree&filepath=nc_py_api%2Fwebhooks.py&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=cloud-py-api#diff-bmNfcHlfYXBpL3dlYmhvb2tzLnB5) | `58.75% <58.75%> (ø)` | |