Add normalize_constant

[blegat]

Extracted from #759

[codecov-io]

Codecov Report

Merging #801 into master will decrease coverage by 0.01%.
The diff coverage is 85.71%.

@@            Coverage Diff             @@
##           master     #801      +/-   ##
==========================================
- Coverage   93.97%   93.96%   -0.02%     
==========================================
  Files          59       59              
  Lines        6690     6691       +1     
==========================================
  Hits         6287     6287              
- Misses        403      404       +1

Impacted Files	Coverage Δ
src/constraints.jl	88.88% <ø> (ø)	⬆️
src/Bridges/Constraint/square.jl	98.27% <100%> (ø)	⬆️
src/Bridges/Constraint/det.jl	98.73% <100%> (ø)	⬆️
src/Bridges/Constraint/geomean.jl	100% <100%> (ø)	⬆️
src/Bridges/Constraint/scalarize.jl	59.45% <100%> (ø)	⬆️
src/Utilities/constraints.jl	85.71% <66.66%> (-14.29%)	⬇️

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