WIP: Add comments with type for exports

[tkers]

Just a little experiment, but it would be nice to be able to enable something like this in the output.

• Pass the TypedModule (from infer) to compile, so type info becomes accessible
• Using (exp.value.info as any).type to get the type of an expression, because we do not have an explicit Node<Untyped> yet.
• The estree types are not fully compatible with recast, in particular the comments work differently. Where estree expects leadingComments: [] and trailingComments: [] on the Expression itself, recast uses a comments: [] fields and checks for a leading or trailing flag inside the Comment (so some as JS.ExpressionStatement hacks were needed).

Result is that

(export foo 42)

compiles to

// type: number
module.exports.foo = 42;