feat(transformer): add async_generator_functions plugin (#6573)

Passed 15/19 tests. The remaining 4 failed tests related to `this` expression, the problem same as I mentioned in #6658. I will fix them in follow-up PRs.

crates/oxc_transformer/src/common/helper_loader.rs

@@ -137,15 +137,23 @@ fn default_as_module_name() -> Cow<'static, str> {
 /// Available helpers.
 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug)]
 pub enum Helper {
+    AwaitAsyncGenerator,
+    AsyncGeneratorDelegate,
+    AsyncIterator,
     AsyncToGenerator,
     ObjectSpread2,
+    WrapAsyncGenerator,
 }
 
 impl Helper {
     const fn name(self) -> &'static str {
         match self {
+            Self::AwaitAsyncGenerator => "awaitAsyncGenerator",
+            Self::AsyncGeneratorDelegate => "asyncGeneratorDelegate",
+            Self::AsyncIterator => "asyncIterator",
             Self::AsyncToGenerator => "asyncToGenerator",
             Self::ObjectSpread2 => "objectSpread2",
+            Self::WrapAsyncGenerator => "wrapAsyncGenerator",
         }
     }
 }

crates/oxc_transformer/src/common/statement_injector.rs

@@ -104,7 +104,6 @@ impl<'a> StatementInjectorStore<'a> {
     }
 
     /// Add multiple statements to be inserted immediately before the target statement.
-    #[expect(dead_code)]
     #[inline]
     pub fn insert_many_before<A, S>(&self, target: &A, stmts: S)
     where

crates/oxc_transformer/src/es2017/async_to_generator.rs

@@ -696,6 +696,15 @@ impl<'a, 'ctx> AsyncGeneratorExecutor<'a, 'ctx> {
     ) {
         BindingMover::new(target_scope_id, ctx).visit_binding_identifier(ident);
     }
+
+    #[inline]
+    pub fn move_bindings_to_target_scope_for_statement(
+        target_scope_id: ScopeId,
+        stmt: &Statement<'a>,
+        ctx: &mut TraverseCtx<'a>,
+    ) {
+        BindingMover::new(target_scope_id, ctx).visit_statement(stmt);
+    }
 }
 
 /// Moves the bindings from original scope to target scope.

crates/oxc_transformer/src/es2017/mod.rs

@@ -6,7 +6,6 @@ use oxc_ast::ast::{Expression, Statement};
 use oxc_traverse::{Traverse, TraverseCtx};
 
 use crate::{es2017::async_to_generator::AsyncToGenerator, TransformCtx};
-#[expect(unused_imports)]
 pub use async_to_generator::AsyncGeneratorExecutor;
 
 #[allow(dead_code)]