feat: Add HTTP Basic auth on the metrics endpoint

[zidokobik]

Referencing #283.

[gaby]

@trallnag Can you take a look at this, it fixes a security issue

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 95.79%. Comparing base (b645ccb) to head (224b34a).
Report is 9 commits behind head on master.

❗ Current head 224b34a differs from pull request most recent head ad7b996. Consider uploading reports for the commit ad7b996 to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #289      +/-   ##
==========================================
+ Coverage   95.68%   95.79%   +0.10%     
==========================================
  Files           5        5              
  Lines         348      357       +9     
==========================================
+ Hits          333      342       +9     
  Misses         15       15              

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