Reset channel members and watchers states when fetching the initial state

[laevandus]

🔗 Issue Links

Resolves ios-issues-tracking/issues/866

🎯 Goal

• Reset members and watches when resetting the channel data to the initial state

📝 Summary

• When we run synchronize then we should reset member data since members might have been removed
• It was fixed for chat state layer and state layer has tests for this already.

🧪 Manual Testing Notes

• Log in with Luke on device 1
• Log in with Han on device 2
• Luke creates a channel with Han
• Han opens the channel and sees that they are both part of the channel
• Han quits the demo app on device 2
• Luke leaves the channel
• Han launches the app again and navigates to the channel

What happens: Luke is shown as a member
Expected: Luke is not shown as a member for Han

☑️ Contributor Checklist

• I have signed the Stream CLA (required)
• This change follows zero ⚠️ policy (required)
• This change should be manually QAed
• Changelog is updated with client-facing changes
• New code is covered by unit tests
• Comparison screenshots added for visual changes
• Affected documentation updated (docusaurus, tutorial, CMS)

[laevandus]

Moved the fix I used for state layer to the completion handler based update method instead. State layer already has tests for this case.

[sonarcloud]

Quality Gate passed

Issues
129 New issues
0 Accepted issues

Measures
0 Security Hotspots
84.5% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud