Flint: Live image with flatfiled and mask correction

This PR provides embedded live tools to apply correction in Flint side

• Process flat field correction
  • Common tomo scans are monitored to record automatically flat and dark
  • This layers are used to process the actual data
• Process mask correction
  • This processing was already existing, but is now integrated in the property window

Plus few improvement of the demo session

• Added mocked shutter to the demo
• Use them to tune the lima tomo simulator
• Create flat and dark functions to mimic a tomo beamline