Basic feature flag + Groups support

[EDsCODE]

What does this PR do?

• Adds support for group api
• Adds support for basic boolean feature flags
• Adjusts handling of distinct/anonymous ids to match posthog-js

Where should the reviewer start?

1. Distinct id handling
2. Group handlers
3. Feature flag handlers

How should this be manually tested? TBD. Bundle and test in a local project?

What are the relevant tickets?

• 17

TODO:

• [x] Trigger feature flag on load
• [x] QA locally
• [ ] Handle decide endpoint more broadly
• [ ] Update docs

[EDsCODE]

The distinct id - anonymous id handling here needs work

[EDsCODE]

Feature flag works. Groups don’t work for some reason. The call is being queued in the client but nothing is making it to the posthog instance

Groups work. Distinct_id wasn't being sent

[EDsCODE]

There's inconsistencies with the test suite. Even on master it seems tests will still fail. I'm suggesting the removal of the workflow for the time being

[liyiy]

Does it make sense to add example functionality usages like we've been doing in the server libraries with example.py for example to make this easier for testing?

[EDsCODE]

Added calls to the example directory projects