feat: add authentication to monitoring setup

[burnerlee]

Deliverables:

• Prometheus and Alertmanager are authenticated using basic HTTP auth.
• Statsd-exporter is configured behind the reverse proxy and requests from staging.eval.ai are only allowed.
• Setup nginx container in dev monitoring env to mimic the staging monitoring setup

To-Do:

• Need to add prometheus_staging.yml to s3 as it contains secrets.
• Need to add .htpasswd file in s3 by generating one using the command htpasswd -c .htpasswd <username>.

[codecov-commenter]

Codecov Report

Merging #3572 (b861659) into master (96968d6) will decrease coverage by 1.45%. The diff coverage is 36.94%.

@@            Coverage Diff             @@
##           master    #3572      +/-   ##
==========================================
- Coverage   72.93%   71.47%   -1.46%     
==========================================
  Files          83       20      -63     
  Lines        5368     3239    -2129     
==========================================
- Hits         3915     2315    -1600     
+ Misses       1453      924     -529     

Impacted Files	Coverage Δ
frontend/src/js/controllers/authCtrl.js	53.91% <6.38%> (-12.95%)	:arrow_down:
frontend/src/js/controllers/profileCtrl.js	79.76% <20.00%> (-13.10%)	:arrow_down:
frontend/src/js/controllers/permissionCtrl.js	36.36% <22.22%> (-63.64%)	:arrow_down:
frontend/src/js/controllers/challengeCtrl.js	63.44% <36.71%> (-10.25%)	:arrow_down:
frontend/src/js/controllers/updateProfileCtrl.js	82.55% <44.44%> (-10.30%)	:arrow_down:
frontend/src/js/controllers/challengeListCtrl.js	95.74% <50.00%> (+1.06%)	:arrow_up:
...ntend/src/js/controllers/challengeHostTeamsCtrl.js	70.50% <66.66%> (-1.18%)	:arrow_down:
frontend/src/js/controllers/teamsCtrl.js	71.17% <75.00%> (ø)
frontend/src/js/controllers/ChallengeInviteCtrl.js	100.00% <100.00%> (ø)
frontend/src/js/controllers/SubmissionFilesCtrl.js	95.45% <100.00%> (ø)
... and 30 more

Impacted Files	Coverage Δ
frontend/src/js/controllers/authCtrl.js	53.91% <6.38%> (-12.95%)	:arrow_down:
frontend/src/js/controllers/profileCtrl.js	79.76% <20.00%> (-13.10%)	:arrow_down:
frontend/src/js/controllers/permissionCtrl.js	36.36% <22.22%> (-63.64%)	:arrow_down:
frontend/src/js/controllers/challengeCtrl.js	63.44% <36.71%> (-10.25%)	:arrow_down:
frontend/src/js/controllers/updateProfileCtrl.js	82.55% <44.44%> (-10.30%)	:arrow_down:
frontend/src/js/controllers/challengeListCtrl.js	95.74% <50.00%> (+1.06%)	:arrow_up:
...ntend/src/js/controllers/challengeHostTeamsCtrl.js	70.50% <66.66%> (-1.18%)	:arrow_down:
frontend/src/js/controllers/teamsCtrl.js	71.17% <75.00%> (ø)
frontend/src/js/controllers/ChallengeInviteCtrl.js	100.00% <100.00%> (ø)
frontend/src/js/controllers/SubmissionFilesCtrl.js	95.45% <100.00%> (ø)
... and 30 more

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