Describe your changes

Features:

• moved AST.Typedef case from direct declaration to indirect declaration behind a pointer
• this reduces the size of the AST type by 90%
• speed is improved by about 30% (somehow memory size reduction helps here with zeroing and moves)
• resulting in a total memory usage reduction in the compiler of 40% (9GB total with GC disabled)
• PCTX was heavily affected by this because it contains a blame field and has many rows
• so this will affect the memory usage of GC-enabled compiler more than current one

Issue ticket number and link

#1895

Checklist before requesting a review

• [ x ] I have performed an AI-assisted self-review of my code.

Can you review my pull request and provide some suggestions?
https://patch-diff.githubusercontent.com/raw/Lambda-Mountain-Compiler-Backend/lambda-mountain/pull/1926.diff

• [ x ] If it is a new feature, I have added thorough tests.
• [ x ] I agree to release these changes under the terms of the permissive MIT license (1).

1. https://github.com/andrew-johnson-4/lambda-mountain/blob/main/LICENSE