✨ Support custom CII_Best_Practices_URLvia environment variable.

[kash2104]

What kind of change does this PR introduce?

This PR updates DefaultCIIBestPracticesClient to support configuring the CII Best Practices base URL via an environment variable.

(Is it a bug fix, feature, docs update, something else?)
feature

• PR title follows the guidelines defined in our pull request documentation

What is the current behavior?

DefaultCIIBestPracticesClient always uses the hard-coded URL https://www.bestpractices.dev when querying CII Best Practices badge data.

What is the new behavior (if this is a feature change)?**

If the CII_BEST_PRACTICES_URL environment variable is set, DefaultCIIBestPracticesClient will use it as the base URL.
If not set, the client falls back to the existing default URL.

• Tests for the changes have been added (for bug fixes/features)

Which issue(s) this PR fixes

Fixes #4315

Special notes for your reviewer

Does this PR introduce a user-facing change?

No

For user-facing changes, please add a concise, human-readable release note to
the release-note

(In particular, describe what changes users might need to make in their
application as a result of this pull request.)

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 69.70%. Comparing base (353ed60) to head (50309bd).
⚠️ Report is 297 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4882      +/-   ##
==========================================
+ Coverage   66.80%   69.70%   +2.89%     
==========================================
  Files         230      251      +21     
  Lines       16602    15649     -953     
==========================================
- Hits        11091    10908     -183     
+ Misses       4808     3867     -941     
- Partials      703      874     +171     

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[spencerschrock]

Thanks, one minor change

[spencerschrock]

/scdiff generate CII-Best-Practices

[github-actions]

Here's a link to the scdiff run

[spencerschrock]

Thanks!