Migrate FileIdGenerator to separate file + refactorings to IR

[Forthoney]

ir.py was a massive file that was impossible to dig through, and this PR aims to resolve that somewhat. Large parts of IR have been refactored (resolved some TODO items, added better type hinting)

[github-actions]

OS:ubuntu-20.04
Sat Nov 25 01:18:49 UTC 2023
intro: 0/2 tests passed.
interface: 6/41 tests passed.
compiler: 0/54 tests passed.
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