Dynamic Installation of RoundCube Plugins

[jawabuu]

Hey @thomascube
This is a 'cross-post' from this issue here regarding roundcube plugins Mailu/Mailu#1326
The PR allows users to install RoundCube Plugins and activate them using environment variables.
It is designed to be entirely optional and to not interfere with the existing installation process.
Could you take a look and let me know if this is something that might be useful for this repo?

[thomascube]

Just an idea to be tested: in a Kubernetes deplyoment, one could maybe install additional plugins using init containers and a command like described here.

[kwisatz]

I like the idea of the PR in Mailu. It might also interfere less with the code in config.docker.inc.php that exists today.