feat: add FeatureFlagProvider

[codeincontext]

Description

In #320 we added server-side generation of feature flags. That populated the initial flags bootstrapped on posthog.init, and we could then query posthog to get the feature flag status

It turns out that this has two problems:

• Posthog is initialised in a useEffect, so the server render and initial client render don't have information about flags
• useAnalyticsService only initialises posthog when cookie consent is granted. If the user denies consent or never interacts with the cookie banner, posthog won't work as expected

This PR:

• Creates FeatureFlagProvider
• Passes bootstrapped server feature flags to FeatureFlagProvider
• Makes useClientSideFeatureFlag consume the provider, and fall back to a bootstrapped value if posthog hasn't loaded flags

Testing:

• We don't have any flags at the moment, but you can play with this on test: temporary branch test for feature flags #354

[vercel]

The latest updates on your projects. Learn more about Vercel for Git ↗︎

Name	Status	Preview	Comments	Updated (UTC)
oak-ai-lesson-assistant	✅ Ready (Inspect)	Visit Preview	💬 Add feedback	Nov 7, 2024 5:50pm

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud

[github-actions]

Playwright test results

 14 passed
 1 skipped

Details

 Open report ↗︎
 15 tests across 14 suites
 2 minutes, 8 seconds
 f72fa5d

Skipped tests

No persona › tests/auth.test.ts › authenticate through Clerk UI

[JBR90]

LGTM, tested the 'cool new feature' and worked as expected

[codeincontext]

LGTM, tested the 'cool new feature' and worked as expected

Great. Thanks Joe

[oak-machine-user]

🎉 This PR is included in version 1.16.0 🎉

The release is available on GitHub release

Your semantic-release bot 📦🚀