Improve CMake by solving all issues trying to build with CUDACLANG

This MR introduces the ability to compile with CUDACLANG. This compiles the code with clang instead of nvcc.

Linkage is non-trivial, and requires more work.

added 11 commits

• 6dec7eb3...efe57994 - 9 commits from branch allen_tdr
• dd002518 - Merge remote-tracking branch 'origin/allen_tdr' into dcampora_allen_tdr_cmake
• 424594b6 - Added allen_host_library.

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added 3 commits

• 424594b6...7fc95f2f - 2 commits from branch allen_tdr
• af11e9de - Merged with allen_tdr.

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added 6 commits

• af11e9de...4e94cd04 - 5 commits from branch allen_tdr
• 8dbb3f16 - Merge remote-tracking branch 'origin/allen_tdr' into dcampora_allen_tdr_cmake

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merged

mentioned in commit ecd99628