Set NC loglevel via ncp

[mwip]

Description
Currently, there is an issue with Nextcloud's logs that are flooded with messages like:

appinfo/app.php is deprecated, use \\OCP\\AppFramework\\Bootstrap\\IBootstrap on the application class instead.

This is discussed here https://github.com/nextcloud/server/issues/23046

Especially in NextCloudPi I fear this means unnecessary wear and tear on the SD card. A solution would be to set the loglevel in config/config.php to something higher than 0 (which is debug logs, https://docs.nextcloud.com/server/15/admin_manual/configuration_server/logging_configuration.html).

This could be implemented as an entry under Config similar to nc-trusted-domains. Unfortunately I am not familiar with PHP, so I am not able to provide an example implementation.