Add rapids_cuda_set_runtime

[robertmaynard]

Description

Add rapids_cuda_set_runtime which is the per target version of rapids_cuda_init_runtime.
Fixes #427

Checklist

• I am familiar with the Contributing Guidelines.
• New or existing tests cover these changes.
• The documentation is up to date with these changes.
• The cmake-format.json is up to date with these changes.
• I have added new files under rapids-cmake/
  • I have added include guards (include_guard(GLOBAL))
  • I have added the associated docs/ rst file and update the api.rst

[vyasr]

Do we need to address the interface/private question you raised before we finalize?

[robertmaynard]

Do we need to address the interface/private question you raised before we finalize?

I think we should address this before merging.

Currently the approach is that we us PUBLIC linking for all targets (except INTERFACE). After thinking about this more I think that PRIVATE by default might be the best approach as it has the least amount of suprises. By that I mean if you call rapids_cuda_set_runtime on a target I don't think users expect it would have an impact on anything that links to that target.

Note: I am ignoring INTERFACE targets from the above. Since INTERFACE targets can only have INTERFACE linking the behavior with those is pre-determined. I do need to update the docs no matter what to explicitly state what behavior you will get based on the target type you provide.

[vyasr]

Thanks! This looks good to me now. The only question I have is whether there are any cases where we would want PUBLIC linking even for non-INTERFACE targets, in which case we'd want it parametrizable. I'm approving since I don't see any important use cases, but please add that option if you do.

[robertmaynard]

/merge