Prototypes booleans and relational operators.
As part of this I removed `FFI/Data/Bool.agda`, because it was getting in the way - we already use `Agda.Builtin.Bool` instead for other cases.
We don't emit type annotations right now for `AstLocal`s in the JSON encoder. This makes it really hard to surface annotations in the Agda implementation. This PR changes it to emit location and type annotations, if present.
