This commit refactors the AST substitution logic to correctly handle
nested expansions and improve the inlining of lambda expressions.
The changes include:
- Extracting the core value from potentially expanded AST nodes before
checking their kind.
- Ensuring that lambda expressions with empty upvalues are correctly
substituted.
- Adding support for inlining global get expressions as AST
substitutions.
- Improving the `UsageInfo` collection to correctly track assigned
values.
Michael Schimmel
0dfcfac7b3