Replace pycuda with cuda-python calls

[orperel]

This change-set deprecates the pycuda usage, which complicated the Wisp installation due to GL extension compilation. Requires pip install cuda-python

Changes:

• pycuda replace with direct cuda api (cuda-python bindings)
• cuda_guard.py have been removed (no longer needed as context bugs are bypassed)
• GLX error messages when closing windows are now gone.
• Support for torch 1.9.1 is fixed.
• pycuda can be used as a fallback by setting the env variable ENABLE_PYCUDA=1
• Fix support for WSL through bypassing cuda-opengl interop.

New Wisp installation:

pip install -r requirements.txt
pip install -r requirements_app.txt
python setup.py develop

Signed-off-by: operel operel@nvidia.com