Add cuda driver cmake dependency

[MrBurmark]

Find CUDAToolkit and depend on CUDA::cuda_driver.

[rhornung67]

Thanks @MrBurmark . I assume you tested this in a RAJA build.

[MrBurmark]

Looks like RAJA is going to have to find CUDAToolkit as well otherwise it doesn't know what CUDA::cuda_driver is.

[rhornung67]

Looks like RAJA is going to have to find CUDAToolkit as well otherwise it doesn't know what CUDA::cuda_driver is.

Grrrf. Should we add that to Arturo's launch docs PR to minimize churn?

[MrBurmark]

I'm afraid of how far this finding will have to go down the lib stack. Presumably, umpire, chai, and anyone else using camp may have to add this.

[rhornung67]

Do we have to wait on BLT support to make it seamless?

[MrBurmark]

I think so, but it doesn't sound like that's coming super soon.

[rhornung67]

Chris said he is working on a BLT release. @white238 can you clarify whether the find cuda toolkit business will be available in that?

[MrBurmark]

Closing this inadequate attempt to fix the config as we're going to revert the changes that necessitated this change #131.