nextcloud-version: feature to throw warning if the repositorry is not reachable

[asltbbg]

Describe the solution you'd like

if the repository is not reachable the check don't list available updates and keeps the ok state and you nerver know thas something is wrong. so it would be nice to see if the repsitory is reachable by the check

maybe the feature is usefull for the [nextcloud-security-scan] and some others to

Additional context

No response

[markuslf]

For nearly all *-version check plugins, EOL dates are taken from

1. Local SQLite DB cache (valid for 24 hours). If not successful...
2. From https://endoflife.date/api (and then cached). If not successful (e.g. if server does not have internet access)...
3. From local JSON definition file endoflifedate.py (definition copied from endoflife.date), and then cached.

Other users wanted the described behavior because many servers don't have internet access, so this is the default. But adding a switch to get a warning if something goes wrong when accessing the Internet makes sense.

[markuslf]

All other plugins that rely on internet access like nextcloud-security-scan already complain and return UNKNOWN if there is something wrong.