[Flagd] offline mode for in-process provider

[Kavindu-Dodan]

Flagd has in-process evaluation capability introduced through PR #327

Similar to the offline in-process mode in Java provider ¹, we should introduce an offline in-process mode for Go provider.

This needs to be followed up after completing the #393

Footnotes

1. • https://github.com/open-feature/java-sdk-contrib/pull/473
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[thisthat]

We should also include the improvement done in open-feature/java-sdk-contrib#614
This would enable mounting a ConfigMap directly on a Pod that contains the FF definition.

[Kavindu-Dodan]

We should also include the improvement done in open-feature/java-sdk-contrib#614 This would enable mounting a ConfigMap directly on a Pod that contains the FF definition.

Opened PR #421 and in that I used flagd's implementation of the file sync. This has proven to work fine (compared to what I found on Java libraries and watchers). I think reusing this reduces complexity and avoids code duplication :)