Don't include extension plugins by default in docker images

[DuckBoss]

Pros: Reduces container sizes for those that don’t need additional functionality.
Cons: Must be properly documented or people will complain that some plugins aren’t working/missing.

It might be a better idea to add a variable while running a docker image to download/install extension plugins as an option during first-run.
If the plugins are already installed, ignore the environment variable at runtime.
Optionally, also add a variable to remove/remove-all extension plugins.

Example:

docker run … -e INSTALL_ALL_EXTENSION_PLUGINS=True
docker run … -e INSTALL_EXTENSION_PLUGINS="plugin1, plugin2, ..."