common/math: Add CalculateAbsPercentageDifference and add DecimalAbsPercentageDifference

[shazbert]

PR Description

• Needed absolute value as it was returning negative values.
• Adds decimal package calc
• Adds vars so that less decimal structs are allocated

Fixes # (issue)

Type of change

Please delete options that are not relevant and add an x in [] as item is complete.

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

How has this been tested

Please describe the tests that you ran to verify your changes. Provide instructions so we can reproduce. Please also list any relevant details for your test configuration and
also consider improving test coverage whilst working on a certain feature or package.

• go test ./... -race
• golangci-lint run
• Test X

Checklist

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation and regenerated documentation via the documentation tool
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally and on Github Actions with my changes
• Any dependent changes have been merged and published in downstream modules

[gloriousCode]

I wouldn't call it a bug to have a negative percentage difference. I would suggest you add CalculateAbsPercentageDifference and DecimalAbsPercentageDifference

[shazbert]

Yeah, I guess they are both valid so it's not a bug, but I would caution adding the difference though as you can get values above 100% in the negative direction, all we are achieving is finding the degree of magnitude, I would say directionality can be applied to the value after if needed? I see that I am starting to furiously agree with you as I type this. So I can add the distinction and people can choose their own destiny. 😆

[codecov]

Codecov Report

Attention: Patch coverage is 95.45455% with 1 line in your changes missing coverage. Please review.

Project coverage is 36.38%. Comparing base (17c2ef2) to head (ad4c3e8).
Report is 2 commits behind head on master.

Files	Patch %	Lines
common/math/math.go	95.45%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #1617   +/-   ##
=======================================
  Coverage   36.37%   36.38%           
=======================================
  Files         422      422           
  Lines      183113   183125   +12     
=======================================
+ Hits        66602    66623   +21     
+ Misses     108466   108459    -7     
+ Partials     8045     8043    -2     

Files	Coverage Δ
common/math/math.go	79.94% <95.45%> (+0.72%)	⬆️

... and 11 files with indirect coverage changes