Add mono_class_set_failure_from_loader_error and use it in a few spots.
Move mono_class_create_from_typedef to use MonoError.

	* class.c (mono_class_create_from_typedef): Do error handling using MonoError
	instead of the loader error for this one.
Add a function to convert from a MonoError to a loader error. Use it with callers of mono_class_create_from_typedef.