feat(php): improve return typehint when repeatedfield (#11734)

Adds the type of the `RepeatedField` to the PHPDoc, e.g.

```php
/**
 * @return \Google\Protobuf\Internal\RepeatedField<int>
 */
```

Whereas before, the `<int>` part was not included.

This is the "getter" counterpart for #4533

Closes #11734

PiperOrigin-RevId: 726881276

Author: bshaffer

php/BUILD.bazel

@@ -47,12 +47,13 @@ _RUNTIME_SOURCES = [
     "src/Google/Protobuf/Internal/MessageBuilderContext.php",
     "src/Google/Protobuf/Internal/OneofDescriptor.php",
     "src/Google/Protobuf/Internal/OneofField.php",
-    "src/Google/Protobuf/PrintOptions.php",
     "src/Google/Protobuf/Internal/RawInputStream.php",
     "src/Google/Protobuf/Internal/RepeatedField.php",
     "src/Google/Protobuf/Internal/RepeatedFieldIter.php",
     "src/Google/Protobuf/Internal/TimestampBase.php",
     "src/Google/Protobuf/OneofDescriptor.php",
+    "src/Google/Protobuf/PrintOptions.php",
+    "src/Google/Protobuf/RepeatedField.php",
 ]
 
 filegroup(

php/ext/google/protobuf/array.c

@@ -646,7 +646,7 @@ void Array_ModuleInit() {
   zend_object_handlers* h;
 
   // RepeatedField.
-  INIT_CLASS_ENTRY(tmp_ce, "Google\\Protobuf\\Internal\\RepeatedField",
+  INIT_CLASS_ENTRY(tmp_ce, "Google\\Protobuf\\RepeatedField",
                    repeated_field_methods);
 
   RepeatedField_class_entry = zend_register_internal_class(&tmp_ce);
@@ -663,6 +663,12 @@ void Array_ModuleInit() {
   h->get_properties = RepeatedField_GetProperties;
   h->get_property_ptr_ptr = RepeatedField_GetPropertyPtrPtr;
 
+  // RepeatedField alias (for backwards compatibility).
+  zend_register_class_alias_ex(
+      "Google\\Protobuf\\Internal\\RepeatedField",
+      strlen("Google\\Protobuf\\Internal\\RepeatedField"),
+      RepeatedField_class_entry, true);
+
   // RepeatedFieldIter
   INIT_CLASS_ENTRY(tmp_ce, "Google\\Protobuf\\Internal\\RepeatedFieldIter",
                    repeated_field_iter_methods);