Suppress CUDA Warnings, master branch (2021.11.11.)

Disabled the "declared but never used" warning for the clients of AthCUDAKernelLib. CUDA 11.4 is mistakenly issuing this warning for the variadic template code of the package. Which I was only able to disable in this global way. ☹

I tried to make the following type of code work for a while:

#pragma diag_suppress = 177
...
// problematic code
...
#pragma diag_default = 177;

I tried with explicit codes, with declared_but_not_referenced, and I also tried with nv_diag_suppress instead of diag_suppress. But the compilation didn't react to any of those. 😦 I was only able to disable the warning through a compiler option in the CMake configuration...

For future reference: The way that I found the 177 code for this warning was by first adding the following for the build:

target_compile_options( AthCUDAKernelLib PUBLIC
   $<$<COMPILE_LANGUAGE:CUDA>:-Xcudafe --display_error_number> )

This is all meant to address the warnings described in ATLINFR-4322.

While at it, I also set CMAKE_CUDA_ARCHITECTURES to compute capability 5.2 by default. This gets rid of the following warnings from our current build:

nvcc warning : The 'compute_35', 'compute_37', 'compute_50', 'sm_35', 'sm_37' and 'sm_50' architectures are deprecated, and may be removed in a future release (Use -Wno-deprecated-gpu-targets to suppress warning).

Which our current log parsing is blind to btw. @aundrus, could you add this pattern (nvcc warning :) as a warning to the NICOS pages?