[wip] Break down default export with variable assignment

[mohsen1]

This change set introduces a new transform that breaks down an invalid code like this:

export default const MyComponent: React.RFC = () => null;

to

const MyComponent: React.RFC = () => null;
export default MyComponent

Fixes #38

[mohsen1]

Getting text of newly added nodes (synthetic nodes) is something I've always struggled with in this repo. Asking the TypeScript team to help me with it here. The failing test is result of trying to access text of a synthetic node.

[mohsen1]

I forked this repo and now maintaining it there. This pull request is moved to
mohsen1#1