Flint: Basic support of parallel scans

This MR provides a basic implementation of parallel scans.

• Update the internal modelization to allow to store all the scans
• Update scan manager to reach the data from all this scans
• Update the progress bar to display many scans
• Update the simulator

For now:

• There is no more conflict between parallel scans
• Only the first discovered scan will have plot displayed
• Others will be ignored (no plots, no images)
• But all will have a progress bar