Adding CUDA NVCC build

[henryiii]

Added to highlight NVCC warnings. See #359.

[henryiii]

Warnings look like this:

/cli11/include/CLI/TypeTools.hpp(143): warning: invalid narrowing conversion from "double" to "int"
          detected during:
            instantiation of "CLI::detail::is_direct_constructible<T, C>::test [with T=int, C=double]" based on template arguments <int, double>
(150): here
            instantiation of class "CLI::detail::is_direct_constructible<T, C> [with T=int, C=double]"
/cli11/include/CLI/Validators.hpp(380): here

/cli11/include/CLI/TypeTools.hpp(143): warning: invalid narrowing conversion from "int" to "double"
          detected during:
            instantiation of "CLI::detail::is_direct_constructible<T, C>::test [with T=double, C=int]" based on template arguments <double, int>
(150): here
            instantiation of class "CLI::detail::is_direct_constructible<T, C> [with T=double, C=int]"
/cli11/include/CLI/Validators.hpp(399): here

/cli11/include/CLI/TypeTools.hpp(143): warning: invalid narrowing conversion from "double" to "__nv_bool"
          detected during:
            instantiation of "CLI::detail::is_direct_constructible<T, C>::test [with T=__nv_bool, C=double]" based on template arguments <__nv_bool, double>
(150): here
            instantiation of class "CLI::detail::is_direct_constructible<T, C> [with T=__nv_bool, C=double]"
/cli11/include/CLI/App.hpp(758): here

[phlptp]

This looks pretty similar to the warning that was blocked on gcc.

[codecov]

Codecov Report

Merging #365 into master will not change coverage.
The diff coverage is n/a.

@@          Coverage Diff          @@
##           master   #365   +/-   ##
=====================================
  Coverage     100%   100%           
=====================================
  Files          12     12           
  Lines        3397   3397           
=====================================
  Hits         3397   3397

Impacted Files	Coverage Δ
include/CLI/TypeTools.hpp	100% <ø> (ø)	⬆️

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[henryiii]

Warning and one build error fixed on NVCC, NVCC is now part of the testing.