Separate system wide dictionary and user level dictionary

> Ideally govarnam would use the file in /usr/share/varnam/ml.vst.learnings as read-only and create a file in ~/.local/share/varnam/learnings/ml.vst.learnings for the user changes

From discussion with Guido in the Matrix room of Varnam, it's better to have a setup like this so the package doesn't need to do an import on post-install

This will be a serious change, so this will be v2.0