openvidu/openvidu-server-kms: install extra Kurento modules

[j1elo]

The Docker image openvidu/openvidu-server-kms for development comes with Kurento Media Server installed:

openvidu/openvidu-server/docker/openvidu-server-kms/Dockerfile

Lines 9 to 14 in e5a8a17

	# Install Kurento Media Server (KMS)
	RUN echo "deb [arch=amd64] http://ubuntu.openvidu.io/6.15.0 bionic kms6" | tee /etc/apt/sources.list.d/kurento.list && \
	apt-key adv --keyserver keyserver.ubuntu.com --recv-keys 5AFA7A83 && \
	apt-get update && \
	apt-get -y install kurento-media-server && \
	rm -rf /var/lib/apt/lists/*

This could also come with the extra modules installed, in case people want to use them. Something like this:

https://github.com/Kurento/kurento-docker/blob/cf20b0a410c0a958fd30f0a8672813d9401c6899/kurento-media-server/Dockerfile#L145-L152

(but first we should see how to fix this: e5a8a17#r54346390)