refactor: delete ModuleSystem's file_data property

There are many `field_data` usages in the platform. Let's categorize them and determine,
which are related to this change and in what way.

- ModuleSystem's argument. This is what we're removing.
- Runtime.field_data. Directly related, as Runtime is ModuleSystem's superclass.
  Analysis below this list is centered around this.
- XBlock.field_data. Not related anymore. Runtime.construct_xblock was passing
  runtime's field_data to the XBlock's constructor, but that was ~8 years ago.
- DescriptorSystem.field_data. Not related anymore. field_data has been removed
  from the constructor long time ago, but you still can see its ancestors
  instantiated with field_data=<value> here and there. It's important to note,
  that it has been added here in the first place, because field_data was required in Runtime.
- DummySystem, CachingDescriptorSystem, ImportSystem. Not related anymore.
  All these classes inherit MakoDescriptorSystem, which inherits DescriptorSystem itself.
  So, see the previous item.
- PreviewModuleSystem, TestModuleSystem, LmsModuleSystem — ModuleSystem's ancestors. Directly related.

Basing on that, the only necessary check is to search for ModuleSystem's ancestors using
`field_data` or `_deprecated_per_instance_field_data`. As there are no such cases, it's safe to remove `field_data`.

Co-authored-by: Paulo Viadanna <paulo@opencraft.com>
Co-authored-by: DubeySandeep <dubeysandeep.in@gmail.com>

xmodule/x_module.py

@@ -1668,7 +1668,6 @@ class ModuleSystem(MetricsMixin, ConfigurableFragmentWrapper, ModuleSystemShim,
         publish=None,
         course_id=None,
         error_descriptor_class=None,
-        field_data=None,
         **kwargs,
     ):
         """
@@ -1692,15 +1691,11 @@ class ModuleSystem(MetricsMixin, ConfigurableFragmentWrapper, ModuleSystemShim,
         publish(event) - A function that allows XModules to publish events (such as grade changes)
 
         error_descriptor_class - The class to use to render XModules with errors
-
-        field_data - the `FieldData` to use for backing XBlock storage.
         """
 
-        # Usage_store is unused, and field_data is often supplanted with an
-        # explicit field_data during construct_xblock.
         kwargs.setdefault('id_reader', getattr(descriptor_runtime, 'id_reader', OpaqueKeyReader()))
         kwargs.setdefault('id_generator', getattr(descriptor_runtime, 'id_generator', AsideKeyGenerator()))
-        super().__init__(field_data=field_data, **kwargs)
+        super().__init__(**kwargs)
 
         self.STATIC_URL = static_url
         self.track_function = track_function