feat(BUX-190): add keys generation

[pawellewandowski98]

Description

• Added methods to generate random set of keys and to get pub from xpriv

Pull Request Checklist

• 📖 I created my PR using provided : CODE_STANDARDS
• 📖 I have read the short Code of Conduct: CODE_OF_CONDUCT
• 🏠 I tested my changes locally.
• ✅ I have provided tests for my changes.
• 📝 I have used conventional commits.
• 📗 I have updated any related documentation.
• 💾 PR was issued based on the Github or Jira issue.

[codecov]

Codecov Report

Attention: 124 lines in your changes are missing coverage. Please review.

Comparison is base (c7df2a4) 38.83% compared to head (8d495cf) 37.44%.
Report is 10 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #166      +/-   ##
==========================================
- Coverage   38.83%   37.44%   -1.40%     
==========================================
  Files          21       23       +2     
  Lines        2585     2681      +96     
==========================================
  Hits         1004     1004              
- Misses       1495     1591      +96     
  Partials       86       86              

Flag	Coverage Δ
unittests	37.44% <0.00%> (-1.40%)	⬇️

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

Files	Coverage Δ
examples/graphql/graphql.go	0.00% <0.00%> (ø)
examples/http/http.go	0.00% <0.00%> (ø)
examples/new_paymail/new_paymail.go	0.00% <0.00%> (ø)
examples/register_xpub/register_xpub.go	0.00% <0.00%> (ø)
examples/keys/keys.go	0.00% <0.00%> (ø)
xpriv/xpriv.go	0.00% <0.00%> (ø)

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[mergify]

This pull request looks stale. Feel free to reopen it if you think it's a mistake.