feat: add reply in private feature

[MohamadJaara]

Summary

Adds support for Reply in private across Kalium and Wire Android.

This lets a user reply privately to a message from a group conversation. The private reply keeps a reference to the original group message, so the receiving side can show the quote when the source message is available.

• Adds a Reply in private action to the message options menu.
• Shows the action only for supported group messages.
• Resolves or creates the sender’s 1:1 conversation.
• Opens the private conversation with the quote already prepared.
• Preserves quote metadata through composer and draft state.
• Supports rendering private-reply quotes, with graceful fallback when quote data is unavailable.

Notes

The new quote field is optional. Old quotes continue to work as before, and clients without the new behavior can still receive the message text.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
1.9% Duplication on New Code

See analysis details on SonarQube Cloud