* fix: unifi deploy hook also update Cloud Key nginx certs
When running on a Unifi Cloud Key device, also deploy to
/etc/ssl/private/cloudkey.{crt,key} and reload nginx. This
makes the new cert available for the Cloud Key management
app running via nginx on port 443 (as well as the port 8443
Unifi Controller app the deploy hook already supported).
Fixes#3326
* Improve settings documentation comments
* Improve Cloud Key pre-flight error messaging
* Fix typo
* Add support for UnifiOS (Cloud Key Gen2)
Since UnifiOS does not use the Java keystore (like a Unifi
Controller or Cloud Key Gen1 deploy), this also reworks
the settings validation and error messaging somewhat.
* PR review fixes
* Detect unsupported Cloud Key java keystore location
* Don't try to restart inactive services
(and remove extra spaces from reload command)
* Clean up error messages and internal variables
* Change to _getdeployconf/_savedeployconf
* Switch from cp to cat to preserve file permissions
