Draft: Create root for flint

This PR test the feasibility of creating a root for flint.

• flint is already a project at pypi
• bliss.flint still need to exist for persistent data in redis
• flint.resources have to be properly packaged
• doc/page probably have to be fixed
• bliss have to be a dependency of flint (for features like RPC, or ROI objects)
• tests/flint_client is difficult to move into flint/tests (we could argue that's BLISS tests)
• tests/scans/test_flint.py have to stay in BLISS
• How to sync flint version with BLISS version?
• move the documentation?

If we want to create a dedicated env for flint

• flint.client is still needed by BLISS (flint have to be part of the bliss env, cyclic dependency)
• We probably have to split flint/flint_client
  • or create different dependencies with a single project