Add jtree cli "upgrade" command for updating/upgrading languages

[breck7]

Might require having the diff work done first.

• Then we can store diffs of grammars versions.
• Then we can maintain a history of all the versions of a language.
• Then we can use those for ensuring typesafe upgrades
• Should be done using convention over configuration?

[breck7]

Closing this for now as not a priority