Refactor Destructure to handle assignments

Renames `DefDestructure` to `Destructure` to better reflect its use in
both definitions and assignments.
Introduces `bind_assign_pattern` to handle assignment destructuring in
the binder.
Adds `test_assign_destructuring` to verify assignment destructuring
functionality.

src/ast/compiler/analyzer.rs

@@ -178,11 +178,11 @@ impl<'a> Analyzer<'a> {
                 )
             }
 
-            BoundKind::DefDestructure { pattern, value } => {
+            BoundKind::Destructure { pattern, value } => {
                 let pat_m = self.visit(Rc::new((**pattern).clone()));
                 let val_m = self.visit(Rc::new((**value).clone()));
                 (
-                    BoundKind::DefDestructure {
+                    BoundKind::Destructure {
                         pattern: Box::new(pat_m),
                         value: Box::new(val_m),
                     },