[CUDA] Add a flag to manually specify the target feature to use with CUDA
Summary:
Normally we parse through the CUDA installation to disover the needed
features. However, we may want to build libraries on targets that do not
currently have CUDA installed but still need to know which features to
make use of when creating the PTX or bitcode. This flag is a simple way
to specify this so we can compile certain codes withotu a valid CUDA
installation.
Ideally this could be done via an -Xarch or simimlar flag but currently
they cannot handle this. We would need to support using an -Xarch flag
that takes multiple arguments that then pass them to the -Xclang
functionality.