chore (anomaly detection): get anomalies proxy API

[mifu67]

Create a proxy for us to fetch anomalies from the frontend

[codecov]

Codecov Report

Attention: Patch coverage is 76.92308% with 27 lines in your changes missing coverage. Please review.

✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
...seer/anomaly_detection/get_historical_anomalies.py	65.67%	15 Missing and 8 partials ⚠️
...nts/endpoints/organization_alert_rule_anomalies.py	88.57%	2 Missing and 2 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master   #76707      +/-   ##
==========================================
+ Coverage   77.17%   78.20%   +1.03%     
==========================================
  Files        6896     6898       +2     
  Lines      306444   306573     +129     
  Branches    50230    50248      +18     
==========================================
+ Hits       236510   239770    +3260     
+ Misses      63468    60386    -3082     
+ Partials     6466     6417      -49     

[JoshFerge]

would it be possible to make this PR a bit smaller / split into multiple?

could start with just the endpoint definition w/ placeholders, then the seer logic as a follow-on.

additionally, if this is a new endpoint, i think it is fine to have it start as EXPERIMENTAL

[mifu67]

would it be possible to make this PR a bit smaller / split into multiple?

could start with just the endpoint definition w/ placeholders, then the seer logic as a follow-on.

additionally, if this is a new endpoint, i think it is fine to have it start as EXPERIMENTAL

Sure, I can break it up

[nhsiehgit]

closed in favor of:
#76934