feat: implement notifications handling for extension logs

[lily-de]

This will allow developers to view logs from their extensions (servers). For the MCP protocol, logs are emitted as notification-type messages, so this PR expands how we handle server responses to include notifications.

[salman1993]

This is great - lots of people asking about this will help a lot. A couple thoughts:

• we have the MCP rusk-sdk repo now (not sure when we plan to start using that repo, it'll be hard to keep things in sync)
• we'll need a way to add the logging capability in mcp-server
• we'll also need a protocol msg for setting the log level - logging/setLevel (that seems to be part of the initial msg flow)