Resolve "Online data processing with feedback"

Closes #3357 (closed)

Replace the demo directory by a proper python project called blissdemo (in analogy with blissdata and blissoda).

• blissdemo project:
  • add ewoks config to the demo session
  • console scripts:
    • bliss-demo-servers: starts beacon, writers, lima devices, ... (ODA servers like celery worker are optional)
    • bliss-demo-session: Bliss shell with the demo session
  • data is saved in the temporary demo directory so it gets cleaned up when stopping all servers
  • add devices to the demo configuration which provide data for data processing:
    • difflab6: LaB6 diffraction patterns
    • mu: diode with the copper attenuation as signal
• bliss_lima_simulators project:
  • a diffraction camera with LaB6 data
• bliss project:
  • FixedDataDiode that yields data based on an axis and fixed x/y data
• Makefile:

  • add new make demo_env_with_oda (creates 3 environments)

  • all environment names are optional arguments

    make demo_env_with_oda [NAME=<name>] [LIMA_NAME=<name>] [ODA_NAME=<name>]

• docs:
  • update "Installation outside ESRF"
  • update "Starting BLISS demo processes"
• README: replace installation instruction with a link (otherwise we have to maintain two documentations of the same thing)

Deployed on CVMFS (which means anyone can run the demo session on visa or slurm): https://gitlab.esrf.fr/singularity/bliss

ODA user script are provided by blissoda: https://blissoda.readthedocs.io/en/latest/demo.html