[reflection] Use handles for several more icalls (#4098)

[reflection] Use handles for several more icalls (#4098)

* [runtime] Remove MonoReflectionGenericMethod typedef.

  - It's not used in the runtime,
  - Unlike other defs in object-internals.h it doesn't seem to have a
    corresponding managed object.

* [reflection] Add mono_field_get_object_handle.

  Reimplement mono_field_get_object and mono_field_get_object_checked in
  terms of it.

* [reflection] Add mono_property_get_object_handle

  Reimplement mono_property_get_object and
  mono_property_get_object_checked in terms of it.

* [reflection] Use handles for FieldInfo,MonoPropertyInfo,ParameterInfo.GetTypeModifiers

* [reflection] Use handles for MonoMethodInfo.get_parameter_info

  - Change mono_param_get_objects_internal to use handles

* [reflection] Cleanup in method_object_construct

* [reflection] Use handles for System.Refleciton.EventInfo.internal_from_handle_type

  - Replace mono_event_get_object_checked by mono_event_get_object_handle
    which uses handles.

* [reflection] Use handles for System.Reflection.MethodBase.GetMethodBodyInternal

  - Replace mono_method_body_get_object_checked by
    mono_method_body_get_object_handle

* [reflection] Remove CHECK_OR_CONSTRUCT, it's dead code.

  All former callers now use CHECK_OR_CONSTRUCT_HANDLE

* [reflection] Use handles for FieldInfo.get_marshal_info and MonoMethodInfo.get_retval_marshal

  - Change mono_reflection_marshal_as_attribute_from_marshal_spec to
    return a handle; fix callers

* [metadata] Add mono_metadata_get_canonical_generic_inst utility function

* [reflection] Use handles for System.Reflection.Module.ResolveMemberToken and 3 more icalls

  - ResolveFieldToken
  - ResolveMethodToken
  - ResolveTypeToken