Add command to completely clean a framework setup

[sebhrusen]

In some cases, when upgrading some frameworks locally using the python runbenchmark my_framework --setup force command, there can be dependency version conflicts during the setup as the previous virtual env was not entirely deleted: this is easily fixed by manually deleting the framework's venv.

Suggestion to simplify this:

• as all the setup + framework's artifacts are now in the following standard subfolders:
  • .setup for setup metadata used by amlb.
  • venv for the Py venv.
  • lib for various downloads. we could then systematically delete those folders when user asks for a force setup.
• keep the force setup as it is to allow fast upgrades, but add commands like --setup clean to only delete those folders, and --setup fresh to clean + do a fresh setup.