[remoting] Convert mono_load_remote_field_new_checked to managed code (#3149)

[remoting] Convert mono_load_remote_field_new_checked to managed code (#3149)

* [remoting] Convert mono_load_remote_field_new_checked to managed code.

* [corlib] Expose runtime struct MonoRemoteClass and MonoClass to managed

Also expose  mono_class_get_type to managed code.

* [corlib] Add Mono.RuntimeClassHandle to encapsulate MonoClass*

and Mono.RuntimeRemoteClassHandle to encapsulate MonoRemoteClass*

* [runtime] mono_marshal_get_ldfld_remote_wrapper invoke the managed TransparentProxy.LoadRemoteFieldNew method directly

Don't bother going through a native call and back out to managed.

* [runtime] Get rid of MONO_WRAPPER_LDFLD_REMOTE

When the MONO_WRAPPER_LDFLD is operating on a proxy, it always invokes
the TransparentProxy::LoadRemoteFieldNew managed method

* [runtime] Remove dead mono_load_remote_field_new_icall

* [mini] Bump AOT file format version

Because we removed the LDFLD_REMOTE wrapper type so all the
MonoWrapperType enum values shifted.