Add Posthog Server Provider

[Cliftonz]

Description:

I would like to propose adding support for PostHog feature flags in the Go SDK of OpenFeature. PostHog provides powerful feature flagging capabilities, and integrating it into the OpenFeature Go SDK would enable users to leverage these features seamlessly.

Motivation:

• PostHog offers a comprehensive set of tools for feature flagging, which includes detailed analytics and user segmentation.
• Integrating PostHog would enhance the flexibility of the OpenFeature Go SDK, allowing users to choose PostHog as their feature flagging provider.
• It would expand the ecosystem and make it easier for teams already using PostHog to adopt OpenFeature.

Proposed Solution:

• Implement a new PostHogProvider for the Go SDK, which will interface with the PostHog API to manage and evaluate feature flags.
• Provide appropriate configuration options to allow users to easily set up and use PostHog with the OpenFeature SDK.

Relevant Resources:

• PostHog Go Feature Flags Tutorial
• PostHog API Documentation

Contribution:

I am happy to contribute to this feature if assigned. Please let me know if you would like me to proceed with the implementation.

Thank you for considering this request!

[Cliftonz]

@beeme1mr @toddbaert Ping

[beeme1mr]

Hey @Cliftonz, that sounds good. I've assigned you the issue. Thanks!

[Cliftonz]

@beeme1mr Thank you! I will raise a PR when I have it done.