Draft: Build on Crusher

This draft merge request is to enable building of Spinifel on Crusher. To enable so, I made the following changes:

In .gitmodules:

1. changed dependency on pycuda to pybindgpu by @jpblaschke (currently this points to a fork branch that can be installed with pip install -e .)
2. changed cufinufft submodule pointer to my branch that also has the pycuda dependency replaced with pybindgpu

In setup/:

1. added in build-from-scratch script instruction to build pybindgpu and cufinufft on Crusher
2. changed module use path in mk_env.sh to use a newer llvm compiler as well as force both cupy and cufinufft to use the same hipfft.so on Cursher

In settings/:

1. added test settings for Crusher in settings

In ./:

1. added Crusher submission script