Support explicit zero and norm in Gauss and Gauss-Kronrod quadrature

[NAThompson]

No description provided.

[NAThompson]

Closes #337

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 95.41%. Comparing base (c6d79d9) to head (951e4e3).
⚠️ Report is 4 commits behind head on develop.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #1456      +/-   ##
===========================================
- Coverage    95.41%   95.41%   -0.01%     
===========================================
  Files          831      831              
  Lines        69588    69588              
===========================================
- Hits         66400    66399       -1     
- Misses        3188     3189       +1     

Files with missing lines	Coverage Δ
...e/boost/math/quadrature/detail/exp_sinh_detail.hpp	96.71% <ø> (ø)
.../boost/math/quadrature/detail/sinh_sinh_detail.hpp	91.26% <ø> (ø)
.../boost/math/quadrature/detail/tanh_sinh_detail.hpp	90.29% <ø> (ø)
include/boost/math/quadrature/exp_sinh.hpp	71.42% <ø> (ø)
include/boost/math/quadrature/gauss.hpp	93.04% <ø> (ø)
include/boost/math/quadrature/gauss_kronrod.hpp	95.45% <ø> (ø)
include/boost/math/quadrature/sinh_sinh.hpp	100.00% <ø> (ø)
include/boost/math/quadrature/tanh_sinh.hpp	91.45% <ø> (ø)
include/boost/math/quadrature/trapezoidal.hpp	93.18% <ø> (ø)

... and 1 file with indirect coverage changes

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