Create container for DV environment

[andreaskurth]

This is just a draft PR to share the current state of work. It needs some clean-up but currently that's not top priority.

Known Issues / TODOs

• util/get-toolchain.py as well as util/container/{start.sh,sudoconf} should be vendored-in from OpenTitan instead of copied as files.
• In order to stay as close to the OT container setup as possible, we probably want to vendor-in the OT Dockerfile and use it as base image for an Ibex-specific image. If that's not possible given the current OT image, we might want to create a more generic OT base image in the upstream OT repo.
  • That would also eliminate the need for an Ibex-specific apt-requirements.txt
• Add a ReadMe describing what the container can be used for and how to use it.