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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