Specify minimum node version

[daikema]

I hit the following warning when installing the (OIDC branch of the) controller on a node:

npm WARN read-shrinkwrap This version of npm is compatible with lockfileVersion@1, but package-lock.json was generated for lockfileVersion@2. I'll try to do my best with it!

Chatting with @veggiesaurus he suggested that we should be using at least node 16 for the controller though at the moment this isn't specified in the config (though as he noted it could be).