Bridge pinned messages between WhatsApp and Matrix

[kalix127]

Summary

This PR adds support for bridging pinned messages between WhatsApp and Matrix in both directions.

WhatsApp to Matrix

When a message is pinned or unpinned on WhatsApp, the bridge updates the room's m.room.pinned_events state event in Matrix instead of sending a text notice. The target message's Matrix event ID is looked up from the bridge database. If the message is not found in the database (e.g. predates the bridge), the pin is silently ignored.

Matrix to WhatsApp

When a user pins or unpins a message from a Matrix client, the bridge diffs the old and new pinned event lists and sends the corresponding PinInChatMessage to WhatsApp. Room power levels for m.room.pinned_events are set when creating new portal rooms so users can pin from Matrix clients.

This direction depends on two upstream changes:

• bridgev2: add PinHandlingNetworkAPI for message pin state changes go#478 (adds PinHandlingNetworkAPI to bridgev2)
• Fix sending pin messages by adding edit attribute tulir/whatsmeow#1106 (fixes getEditAttribute for pin messages)

Files changed

pkg/connector/wamsgtype.go: Added PinInChatMessage message type detection
pkg/connector/handlewhatsapp.go: Added handleWAPinInChat() for WhatsApp to Matrix pin state updates
pkg/connector/handlematrix.go: Added HandleMatrixPinChange() and sendPinInChat() for Matrix to WhatsApp
pkg/connector/capabilities.go: Added StatePinnedEvents to room state features
pkg/connector/chatinfo.go: Added StatePinnedEvents power levels for DM and group rooms

Closes #731

Checklist

• I have read and followed the contributing guidelines at https://docs.mau.fi/bridges/general/contributing.html