branch: fluent

[jessegreenberg]

A branch for phetsims/joist#992. This will require significant changes to the logic needed to create strings so keeping on a branch until we confirm this is the way forward.

[jessegreenberg]

The strings in GFL/GFL:B/ISLC make this test very challenging, there are lots of refactored words and phrases that are reassembled into sentences across these repos that make i18n very difficult. I think translation will require rewriting a lot of this code.

This is going to be too time consuming for this test, we are going to try a different sim instead.

Ill keep the branch until phetsims/joist#992 is closed.