[connectors][live share chat]: integrate the LiveShare chat to the session message in the channels

[legomushroom]

When an LS session starts, we post a message notification about the session to the connected channels:

On the LiveShare side, we open a session chat as a webview to the right:

Would be great to interconnect the channel message reply thread with the Live Share Chat so users can use either. This also makes the session chat and log to be persisted in the team's communication channel.