hosted projects (#8627)

- **Allow joining a hosted project**

You can't yet do anything in a hosted project, but you can join it and
look how empty it is.

Release Notes:

- N/A

crates/rpc/src/proto.rs

@@ -206,6 +206,7 @@ messages!(
     (JoinChannelChat, Foreground),
     (JoinChannelChatResponse, Foreground),
     (JoinProject, Foreground),
+    (JoinHostedProject, Foreground),
     (JoinProjectResponse, Foreground),
     (JoinRoom, Foreground),
     (JoinRoomResponse, Foreground),
@@ -329,6 +330,7 @@ request_messages!(
     (JoinChannel, JoinRoomResponse),
     (JoinChannelBuffer, JoinChannelBufferResponse),
     (JoinChannelChat, JoinChannelChatResponse),
+    (JoinHostedProject, JoinProjectResponse),
     (JoinProject, JoinProjectResponse),
     (JoinRoom, JoinRoomResponse),
     (LeaveChannelBuffer, Ack),