Updates to some AzCore functions a while ago made some path functions
strip off a trailing slash, which caused bad paths to be used when
loading middleware data. Updated the code to use better path APIs.
Remove:
- CryCommon/CryExtension/*
- CryCommon/Serialization/*
- Sandbox/Plugins/EditorCommon/QPropertyTree/*
- All related CryCommon interfaces
- All CrySystem implementations
- Various related Editor classes