[Alignment]Allow member lookup from call when members in request are empty

[ipavlidakis]

🔗 Issue Links

https://getstream.slack.com/archives/C07UG155ERE/p1738777320325749?thread_ts=1738678288.567589&cid=C07UG155ERE

📝 Summary

When a call is being created from another device than the one actually starting it, we need a way to provide nil value for members. When we do, the client doesn't have to provide the members of the call and instead the value will be filled from the backend. This comes closer to the implementation that React and Android have.

☑️ Contributor Checklist

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

[Stream-SDK-Bot]

SDK Size

title	develop	branch	diff	status
StreamVideo	7.46 MB	7.46 MB	0 KB	🟢
StreamVideoSwiftUI	2.07 MB	2.07 MB	0 KB	🟢
StreamVideoUIKit	2.21 MB	2.21 MB	0 KB	🟢
StreamWebRTC	9.85 MB	9.85 MB	0 KB	🟢

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
100.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud