Refactor derivation to pick the version that supports the current CUDA version.
Based on the implementation of the same concept in the cudnn derivation.
Add derivation for TensorRT 8, a high-performance deep learning interface SDK
from NVIDIA, which is at this point non-redistributable. The current version
aldo requires CUDA 11, so this is left out of the cudaPackages_10* scopes.
There are many different versions of the `cudatoolkit` and related
cuda packages, and it can be tricky to ensure they remain compatible.
- `cudaPackages` is now a package set with `cudatoolkit`, `cudnn`, `cutensor`, `nccl`, as well as `cudatoolkit` split into smaller packages ("redist");
- expressions should now use `cudaPackages` as parameter instead of the individual cuda packages;
- `makeScope` is now used, so it is possible to use `.overrideScope'` to set e.g. a different `cudnn` version;
- `release-cuda.nix` is introduced to easily evaluate cuda packages using hydra.
