Start defining follow protocol

Co-Authored-By: Nathan Sobo <nathan@zed.dev>

crates/rpc/src/proto.rs

@@ -175,7 +175,8 @@ messages!(
     (UpdateLanguageServer, Foreground),
     (LeaveChannel, Foreground),
     (LeaveProject, Foreground),
-    (OpenBuffer, Background),
+    (OpenBufferById, Background),
+    (OpenBufferByPath, Background),
     (OpenBufferForSymbol, Background),
     (OpenBufferForSymbolResponse, Background),
     (OpenBufferResponse, Background),
@@ -223,7 +224,8 @@ request_messages!(
     (GetUsers, GetUsersResponse),
     (JoinChannel, JoinChannelResponse),
     (JoinProject, JoinProjectResponse),
-    (OpenBuffer, OpenBufferResponse),
+    (OpenBufferById, OpenBufferResponse),
+    (OpenBufferByPath, OpenBufferResponse),
     (OpenBufferForSymbol, OpenBufferForSymbolResponse),
     (Ping, Ack),
     (PerformRename, PerformRenameResponse),
@@ -255,7 +257,8 @@ entity_messages!(
     GetProjectSymbols,
     JoinProject,
     LeaveProject,
-    OpenBuffer,
+    OpenBufferById,
+    OpenBufferByPath,
     OpenBufferForSymbol,
     PerformRename,
     PrepareRename,