feat(flagd): Context value hydration

[aepfli]

This pr adds context value hydration to the in-process evaluator.

This means, that flagd will provide contextual attributes on connection startup which will be used for inprocess evaluation, like defined in the spec.

https://flagd.dev/reference/specifications/providers/#sync-metadata-properties-in-the-evaluation-context

Follow-up:

• make contextEnricher a config attribute

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 94.28%. Comparing base (b0dac08) to head (1d46ae8).
Report is 4 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #195      +/-   ##
==========================================
+ Coverage   94.13%   94.28%   +0.15%     
==========================================
  Files          17       18       +1     
  Lines         903      928      +25     
==========================================
+ Hits          850      875      +25     
  Misses         53       53              

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[toddbaert]

Approving but consider the my comment.