Private dependency on Thrift for Dart

[toddbeckman-wf]

The Dart library has a private dependency but this project is open source.

Is Dart officially supported? If so, should there be a note to consumers about updating their own Thrift packages to work with Frugal? If not, should it be documented that Dart is not fully supported yet?

[brianshannan-wf]

It's a somewhat unfortunate coincidence of thrift not publishing dart bindings to pub and dart not releasing 1.25 which has support for git dependencies at non-root locations in the repository, one of those things happening would allow us to not use any private dependencies