Add Geohashing Feature with Unit Tests

[ngtduc693]

This is a new feature for encoding geographic coordinates into Geohash strings using the provided Encode method. The tests have been updated to include various random locations across Vietnam, ensuring the accuracy and reliability of the Geohash encoding process.

• I have performed a self-review of my code
• My code follows the style guidelines of this project
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Comments in areas I changed are up to date
• I have added comments to hard-to-understand areas of my code
• I have made corresponding changes to the README.md

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 95.05%. Comparing base (56ca719) to head (a80e22f).
Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #486      +/-   ##
==========================================
- Coverage   95.06%   95.05%   -0.02%     
==========================================
  Files         256      257       +1     
  Lines       10624    10669      +45     
  Branches     1498     1503       +5     
==========================================
+ Hits        10100    10141      +41     
- Misses        400      403       +3     
- Partials      124      125       +1     

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[ngtduc693]

@siriak Hi there
In this PR, all modified and coverable lines are covered by tests ✅ here

But the whole project's rate is affected because there are other people's code segments that lack unit tests. so what should I do or because other people's code I may not understand

[siriak]

Looks good, thanks!

[siriak]

The issue with fluctuating coverage is tracked in #465. If you have time, could you help with that? It's very annoying