ssh: Fix abs paths in file history & repeated go-to-def (#19027)

This fixes two things:

- Go-to-def to absolute paths (i.e. opening stdlib files) multiple times
(opening, dropping, and re-opening worktrees)
- Re-opening abs paths from the file picker history that were added
there by go-to-def


Release Notes:

- N/A

---------

Co-authored-by: Bennet <bennet@zed.dev>

crates/proto/src/proto.rs

@@ -364,6 +364,7 @@ messages!(
     (CheckFileExists, Background),
     (CheckFileExistsResponse, Background),
     (ShutdownRemoteServer, Foreground),
+    (RemoveWorktree, Foreground),
 );
 
 request_messages!(
@@ -486,7 +487,8 @@ request_messages!(
     (LspExtSwitchSourceHeader, LspExtSwitchSourceHeaderResponse),
     (AddWorktree, AddWorktreeResponse),
     (CheckFileExists, CheckFileExistsResponse),
-    (ShutdownRemoteServer, Ack)
+    (ShutdownRemoteServer, Ack),
+    (RemoveWorktree, Ack)
 );
 
 entity_messages!(