test(es/transforms): Add tests about preserving top-level directives (#6518)

**Related issue:**

 - Closes #6508.

Author: kdy1

crates/swc/tests/fixture/issues-6xxx/6508/1/input/.swcrc

@@ -0,0 +1,5 @@
+{
+    "jsc": {
+        "target": "es5"
+    }
+}

crates/swc/tests/fixture/issues-6xxx/6508/1/input/index.js

@@ -0,0 +1,2 @@
+'use client';
+foo(() => { })

crates/swc/tests/fixture/issues-6xxx/6508/1/output/index.js

@@ -0,0 +1,2 @@
+"use client";
+foo(function() {});

crates/swc/tests/fixture/issues-6xxx/6508/2/input/.swcrc

@@ -0,0 +1,5 @@
+{
+    "jsc": {
+        "target": "es5"
+    }
+}

crates/swc/tests/fixture/issues-6xxx/6508/2/input/index.js

@@ -0,0 +1,6 @@
+'use client';
+
+
+export class Foo {
+    foo() { }
+}

crates/swc/tests/fixture/issues-6xxx/6508/2/output/index.js

@@ -0,0 +1,16 @@
+"use client";
+import _class_call_check from "@swc/helpers/src/_class_call_check.mjs";
+import _create_class from "@swc/helpers/src/_create_class.mjs";
+export var Foo = /*#__PURE__*/ function() {
+    "use strict";
+    function Foo() {
+        _class_call_check(this, Foo);
+    }
+    _create_class(Foo, [
+        {
+            key: "foo",
+            value: function foo() {}
+        }
+    ]);
+    return Foo;
+}();

crates/swc/tests/fixture/issues-6xxx/6508/3/input/.swcrc

@@ -0,0 +1,5 @@
+{
+    "jsc": {
+        "target": "es5"
+    }
+}

crates/swc/tests/fixture/issues-6xxx/6508/3/input/index.js

@@ -0,0 +1,6 @@
+'use client';
+
+
+export var Foo = {
+    foo() { }
+}

crates/swc/tests/fixture/issues-6xxx/6508/3/output/index.js

@@ -0,0 +1,4 @@
+"use client";
+export var Foo = {
+    foo: function foo() {}
+};