[ObjC] Create a shared ObjC processor for Macho and DSC views

Both the Macho and DSC views need to process Objective-C but have separate processor classes. It would appear that the DSC version was largely a copy and paste of the Macho view one, with some modifications. The majority of code overlaps between the 2 so it doesn't make sense to maintain 2 and copy and paste improvements/fixes between them.

This commit fixes that by creating a base Objective-C processor that contains the shared code. View specific code is implemented in the respective subclasses for the views. Although there is very little view specific code for each.