feat(new-route): added endpoint to call NC getAbsoluteURL

[oleksandr-nc]

This is needed to resolve the following issue: nextcloud/context_agent#46

The endpoint will be backported to Nextcloud 31.

You can test it with the following snippet:

print(nc.ocs("GET", f"{nc._session.ae_url}/info/nextcloud_url/absolute", json={"url": "some_url"}))

P.S. After we merge this, it might be a good idea to add a method to nc_py_api to allow calling it more cleanly.

[oleksandr-nc]

/backport to stable31

[kyteinsky]

🚀