Reconcile debugger and save state stuff into a single implementation.

Fixes #497 and fixes #496.
Still rough edges, but at least less duplication.

src/xenia/cpu/ppc/testing/ppc_testing_main.cc

@@ -189,7 +189,7 @@ class TestRunner {
     memory->Reset();
 
     // Setup a fresh processor.
-    processor.reset(new Processor(nullptr, memory.get(), nullptr, nullptr));
+    processor.reset(new Processor(memory.get(), nullptr));
     processor->Setup();
     processor->set_debug_info_flags(DebugInfoFlags::kDebugInfoAll);