patcher: refactor (#808)

## Link to GitHub Issue or related Pull Request, if one exists
n/a

## Description of change
Refactor patch manager.

This one file had the UI logic, config save/load, parsing patches JSON,
applying memory patches, everything all in one cpp file. Refactor and
separate out the layers.

## Testing
Sanity checked patch workflows.

src/spice2x/CMakeLists.txt

@@ -615,6 +615,12 @@ set(SOURCE_FILES ${SOURCE_FILES}
         overlay/windows/popn_sub.cpp
         overlay/windows/wnd_manager.cpp
 
+        # patcher
+        patcher/config.cpp
+        patcher/lifecycle.cpp
+        patcher/loader.cpp
+        patcher/runtime.cpp
+
         # external
         external/easywsclient/easywsclient.cpp