Revert "cl-ast: Unify break, return, and unary expressions"

This reverts commit adb0fd229c.

compiler/cl-repl/examples/yaml.rs

@@ -409,6 +409,8 @@ pub mod yamlify {
                 ExprKind::While(k) => k.yaml(y),
                 ExprKind::If(k) => k.yaml(y),
                 ExprKind::For(k) => k.yaml(y),
+                ExprKind::Break(k) => k.yaml(y),
+                ExprKind::Return(k) => k.yaml(y),
                 ExprKind::Continue => {
                     y.key("Continue");
                 }
@@ -567,6 +569,18 @@ pub mod yamlify {
                 .yaml(fail);
         }
     }
+    impl Yamlify for Break {
+        fn yaml(&self, y: &mut Yamler) {
+            let Self { body } = self;
+            y.key("Break").yaml(body);
+        }
+    }
+    impl Yamlify for Return {
+        fn yaml(&self, y: &mut Yamler) {
+            let Self { body } = self;
+            y.key("Return").yaml(body);
+        }
+    }
     impl Yamlify for Literal {
         fn yaml(&self, y: &mut Yamler) {
             y.value(format_args!("\"{self}\""));