refactor: Pull db logic out of BaseHistoryInfra

[metlos]

… such that it can be reused by other services.

This is a relatively simple refactoring that pulls database and repository related functionality out of BaseHistoryInfra into a BaseService a base class reusable by other services and DatabaseRetries that concentrates the retry logic into one place.

This is support work for session scoring but stands on its own so I'm not adding it into the PR stack for the session scoring.

[codecov]

Codecov Report

❌ Patch coverage is 92.06349% with 15 lines in your changes missing coverage. Please review.
✅ Project coverage is 83.80%. Comparing base (57f4ed4) to head (ef4fbf1).

Files with missing lines	Patch %	Lines
backend/tarsy/repositories/retries.py	92.30%	8 Missing ⚠️
backend/tarsy/services/base_service.py	91.25%	7 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #273   +/-   ##
=======================================
  Coverage   83.79%   83.80%           
=======================================
  Files         143      145    +2     
  Lines       13543    13595   +52     
=======================================
+ Hits        11349    11393   +44     
- Misses       2194     2202    +8     

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