Add ability to select GPUs

 Updates to out-of-context synth

Offline docker image

Merge branch 'feature/offline_docker_image' of github.com:Xilinx/finn into feature/offline_docker_image

Feature/pre commit adherence

Use Brevitas 0.6.0

Added debug-statements hook again, but it now explicitly excludes the build_dataflow.py file, due to the hook ignoring # NOQA commands.

Feature/issue templates

Minor updates to CNV notebook