Add remove channel method

Move test client fields into appstate and fix tests

Co-authored-by: max <max@zed.dev>

crates/rpc/src/proto.rs

@@ -231,6 +231,7 @@ messages!(
     (UpdateBuffer, Foreground),
     (UpdateBufferFile, Foreground),
     (UpdateContacts, Foreground),
+    (RemoveChannel, Foreground),
     (UpdateChannels, Foreground),
     (UpdateDiagnosticSummary, Foreground),
     (UpdateFollowers, Foreground),
@@ -296,6 +297,7 @@ request_messages!(
     (RespondToContactRequest, Ack),
     (RespondToChannelInvite, Ack),
     (JoinChannel, JoinRoomResponse),
+    (RemoveChannel, Ack),
     (RenameProjectEntry, ProjectEntryResponse),
     (SaveBuffer, BufferSaved),
     (SearchProject, SearchProjectResponse),