dillon1000/react

[babel] Inject React import if Forget compiled the function

Updates our Babel plugin to add an import to React if we succesfully compiled a 
function and cached one or more values. For now this logic is entirely in the 
Babel plugin itself, but long term we should move this into codegen and teach 
Forget to start the pipeline by lowering the whole Program node to an HIR (which 
would also allow us to understand imports and other module scope values being 
used). Right now it's not possible to add in codegen (without some ugly code) as 
a file containing multiple components would result in duplicate imports being 
generated