fix: the following issues

fix conversion from inner opaque type for when and assignment
This fixes Clause being used in cases where ListClause or TupleClause should be used
Reset defined and zero arg functions between each code gen
Fixes for optimizations when encountering shadowed variables

crates/uplc/src/optimize.rs

@@ -1,5 +1,5 @@
 use crate::{
-    ast::{Name, Program},
+    ast::{Name, NamedDeBruijn, Program},
     parser::interner::Interner,
 };
 
@@ -12,5 +12,10 @@ pub fn aiken_optimize_and_intern(program: Program<Name>) -> Program<Name> {
 
     interner.program(&mut program);
 
+    // Use conversion to Debruijn to prevent optimizations from affecting shadowing
+    let program_named: Program<NamedDeBruijn> = program.try_into().unwrap();
+
+    let program: Program<Name> = program_named.try_into().unwrap();
+
     program.lambda_reduce().inline_reduce()
 }