variable reorg and simplification

[maskarb]

This PR builds on #161. Move the prefix koku to the API directory so that it can be imported elsewhere. When we need to change koku to costmanagement, we will only need to update one place instead of many.

[codecov]

Codecov Report

Merging #165 (70babc1) into main (36edc8e) will increase coverage by 0.81%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main     #165      +/-   ##
==========================================
+ Coverage   87.87%   88.69%   +0.81%     
==========================================
  Files          10       10              
  Lines        1468     1468              
==========================================
+ Hits         1290     1302      +12     
+ Misses        107       99       -8     
+ Partials       71       67       -4     

Flag	Coverage Δ
unittests	88.69% <100.00%> (+0.81%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
dirconfig/dirconfig.go	95.65% <100.00%> (ø)
storage/storage.go	95.50% <100.00%> (ø)
controllers/kokumetricsconfig_controller.go	81.92% <0.00%> (+2.81%)	⬆️

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[myersCody]

LGTM