move EncodeUserIdentifier & signup helper functions

[MatousJobanek]

move EncodeUserIdentifier function here and add a few UserSignup helper function. The most important one is the WithEncodedName one - to have an easy way of using the encoded value as the name of the UserSignup and the original value as the preffered username.

KUBESAW-254

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 78.47%. Comparing base (8e02342) to head (609c649).
Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #452      +/-   ##
==========================================
+ Coverage   78.23%   78.47%   +0.23%     
==========================================
  Files          49       49              
  Lines        2444     2471      +27     
==========================================
+ Hits         1912     1939      +27     
  Misses        478      478              
  Partials       54       54              

Files with missing lines	Coverage Δ
pkg/usersignup/usersignup.go	100.00% <100.00%> (ø)

[mfrancisc]

Nice 👍

[alexeykazakov]

👍