add CI build matrix, refactoring, linting

[casperdcl]

• unify scripts under model dirs
  • fix cpl-{replit,t5} vs cdr-{replit,t5} typo in build scripts
  • fast-fail build/tests in scripts
  • move scripts/*_*.sh -> *-*/build.sh

    for f in scripts/*.sh; do
      model=$(basename -s .sh $f | sed s/_/-/g)
      sed -i "s#/$model##g" $f
      git mv $f $model/build.sh
    done

• add build.sh --flags support
• add CI docker build matrix (fixes Github Actions to handle build and test of the containers  #49)
  • fix builds (skip GPU tests, check env vars, multi-arch --load, etc)
• use self-hosted GPU runners for testing
• fix caching (fixes Docker images are not caching in the correct manner #50)
  • see e.g. this build clearly has caching working
• drop CI pre-commit/action in favour of app
• purge unused config & files
• add more pre-commit hooks & flake8 tests
  • fix detected errors
• unify config under pyproject.toml <= setup.cfg, pytest.ini
• open follow-up issues
  • Serve llama 2  #56 (comment)
  • fix dfs-dalle #66
  • fix cht-dolly-v2 #67
  • update md & online docs

[filopedraz]

@casperdcl, some changes to main branch due to new services.