ssh remoting: Show error message if project path does not exist (#18343)

This now shows an error message if you try open a project over SSH that
doesn't exist. If it's a possible file-path though, it acts like Zed's
`cli` and opens the file so that it can be created.

- Works: `cargo run ssh://127.0.0.1/~/folder-exists/file-does-not-exist`
— this will open `file-does-not-exist`
- Shows error: `cargo run
ssh://127.0.0.1/~/folder-does-not-exist/file-does-not-exist` — this will
show an error

Release Notes:

- N/A

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

crates/project/src/worktree_store.rs

@@ -18,7 +18,7 @@ use gpui::{
 use postage::oneshot;
 use rpc::{
     proto::{self, SSH_PROJECT_ID},
-    AnyProtoClient, TypedEnvelope,
+    AnyProtoClient, ErrorExt, TypedEnvelope,
 };
 use smol::{
     channel::{Receiver, Sender},
@@ -207,7 +207,7 @@ impl WorktreeStore {
         cx.background_executor().spawn(async move {
             match task.await {
                 Ok(worktree) => Ok(worktree),
-                Err(err) => Err(anyhow!("{}", err)),
+                Err(err) => Err((*err).cloned()),
             }
         })
     }