Updated the registration.py script register_engine_path function to add

a key, value mapping of engine name to engine path in the
o3de_manifest.json file

Added a pytest to validate the new engine_name -> engine_path
functionality and registered those test with CTest.

Fixed miscellaneous issues in the registration.py around incorrect
return values for get_*_data functions where some of the returns values
were integers where the return value should have been None

scripts/CMakeLists.txt

@@ -11,5 +11,6 @@
 
 add_subdirectory(detect_file_changes)
 add_subdirectory(commit_validation)
+add_subdirectory(o3de)
 add_subdirectory(project_manager)
 add_subdirectory(ctest)