8201: Fix recursive macro statements expansion r=edwin0cheng a=edwin0cheng
This PR attempts to properly handle macro statement expansion by implementing the following:
1. Merge macro expanded statements to parent scope statements.
2. Add a new hir `Expr::MacroStmts` for handle tail expression infer.
PS : The scope of macro expanded statements are so strange that it took more time than I thought to understand and implement it :(
Fixes #8171
Co-authored-by: Edwin Cheng <edwin0cheng@gmail.com>
c8066ebd17