[Fix]Update deviceToken to empty once unregister void notifications

[ipavlidakis]

📝 Summary

Provide a consistent mechanism for consumers of CallKitAdapter to remove devices for a user account.

Docs update PR: here

☑️ Contributor Checklist

• [x] I have signed the Stream CLA (required)
• [x] This change follows zero ⚠️ policy (required)
• [x] This change should receive manual QA
• [x] Changelog is updated with client-facing changes
• [x] 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	7.61 MB	7.61 MB	0 KB	🟢
StreamVideoSwiftUI	2.18 MB	2.18 MB	0 KB	🟢
StreamVideoUIKit	2.31 MB	2.31 MB	0 KB	🟢
StreamWebRTC	8.69 MB	8.69 MB	0 KB	🟢

[sonarcloud[bot]]

Quality Gate passed

Issues
126 New issues
0 Accepted issues

Measures
0 Security Hotspots
78.9% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud