Add CUDA support to decimal32 and decimal64 basic ops

[mborland]

Adds CUDA support for decimal32 and decimal64 operators add, sub, mul, and div

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 99.1%. Comparing base (fe54452) to head (62e5473).

Additional details and impacted files

@@           Coverage Diff           @@
##           develop    #719   +/-   ##
=======================================
  Coverage     99.1%   99.1%           
=======================================
  Files          230     230           
  Lines        16432   16432           
  Branches      1781    1781           
=======================================
  Hits         16278   16278           
  Misses         154     154           

Files	Coverage Δ
include/boost/decimal/decimal32.hpp	98.8% <100.0%> (ø)
include/boost/decimal/decimal64.hpp	99.3% <100.0%> (ø)

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