Implement Core to AstExpression Translation

[iamrecursion]

Summary

In order to reconnect core to the working interpreter, we need to implement a generator for the old compiler's IR type from Core.

Value

We have introduced Core into the mix while still having a working interpreter, allowing us to start to move the existing analysis into well-principled passes on the new core language.

Specification

• Using existing machinery from luna-package fails to compile on Windows #276, translate the new Core representation to the current IR.
• This translation should be done at a high level of abstraction using Core.Sugar constructs directly. While this can't persist permanently, it is good enough for now.
• No semantic information should be lost (for supported constructs).

Acceptance Criteria & Test Cases

• Core can be translated into the old compiler IR.
• No tests are necessary as this process will go away soon.