[FEATURE] Create implementation to UserIdGenerator

[kaduartur]

- What I did

related #370

• I created implementation to UserIdGenerator

- How to verify it

• Run make unit-test

- Description for the changelog

[codecov-commenter]

Codecov Report

Merging #379 into feature/metrics will increase coverage by 0.06%.
The diff coverage is 63.63%.

@@                 Coverage Diff                 @@
##           feature/metrics     #379      +/-   ##
===================================================
+ Coverage            65.61%   65.67%   +0.06%     
===================================================
  Files                   80       81       +1     
  Lines                 2716     2727      +11     
===================================================
+ Hits                  1782     1791       +9     
  Misses                 750      750              
- Partials               184      186       +2     

Impacted Files	Coverage Δ
pkg/metric/user_id_generator.go	63.63% <63.63%> (ø)
pkg/formula/watcher/watcher.go	76.47% <0.00%> (+5.88%)	⬆️

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