remove es20xx prefixes from plugins and rename folders (#6575)

packages/babel-plugin-transform-classes/test/fixtures/loose-classCallCheck/with-constructor/actual.js

@@ -0,0 +1,11 @@
+class A {
+  constructor() {
+    console.log('a');
+  }
+}
+
+class B {
+  b() {
+    console.log('b');
+  }
+}

packages/babel-plugin-transform-classes/test/fixtures/loose-classCallCheck/with-constructor/expected.js

@@ -0,0 +1,17 @@
+let A = function A() {
+  console.log('a');
+};
+
+let B =
+/*#__PURE__*/
+function () {
+  function B() {}
+
+  var _proto = B.prototype;
+
+  _proto.b = function b() {
+    console.log('b');
+  };
+
+  return B;
+}();