[WIP][devel] Fix determination and usage of platform from config
- Add new utility in Core.Utilities.ProductionEnvironment to get the CMTCONFIG values compatible with the current machine from the /Operations/PlatformsToConfigs section and no longer from /Resources (i.e. no longer use getDIRACPlatform)
- Modify dirac-architecture to use the above
- Modify JobDB.py to use the above
Replaces MR !361 (closed)