Add integer and string support for NdArray values (second attempt)

[PaulVanSchayck]

Second attempt (first attempt)

Adds support for integer and string data types in NdArray values, aligning with the OGC CoverageJSON spec.

Added relevant tests for integer and string case.

[codecov]

Codecov Report

Attention: Patch coverage is 96.55172% with 1 line in your changes missing coverage. Please review.

Project coverage is 94.01%. Comparing base (5809d8c) to head (831727c).
Report is 24 commits behind head on master.

Files with missing lines	Patch %	Lines
src/covjson_pydantic/coverage.py	90.90%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master      #20      +/-   ##
==========================================
+ Coverage   93.97%   94.01%   +0.04%     
==========================================
  Files           9        9              
  Lines         282      301      +19     
==========================================
+ Hits          265      283      +18     
- Misses         17       18       +1     

Flag	Coverage Δ
unittests	94.01% <96.55%> (+0.04%)	⬆️

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

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

---

🚨 Try these New Features:

• Flaky Tests Detection - Detect and resolve failed and flaky tests