Restructure remote client crate, consolidate SSH logic (#36967)

This is a pure refactor that consolidates all SSH remoting logic such
that it should be straightforward to add another transport to the
remoting system.

Release Notes:

- N/A

---------

Co-authored-by: Mikayla Maki <mikayla.c.maki@gmail.com>

crates/terminal_view/src/terminal_element.rs

@@ -1403,7 +1403,7 @@ impl InputHandler for TerminalInputHandler {
                 window.invalidate_character_coordinates();
                 let project = this.project().read(cx);
                 let telemetry = project.client().telemetry().clone();
-                telemetry.log_edit_event("terminal", project.is_via_ssh());
+                telemetry.log_edit_event("terminal", project.is_via_remote_server());
             })
             .ok();
     }

crates/terminal_view/src/terminal_panel.rs

@@ -481,17 +481,28 @@ impl TerminalPanel {
         window: &mut Window,
         cx: &mut Context<Self>,
     ) -> Task<Result<WeakEntity<Terminal>>> {
-        let Ok((ssh_client, false)) = self.workspace.update(cx, |workspace, cx| {
-            let project = workspace.project().read(cx);
-            (
-                project.ssh_client().and_then(|it| it.read(cx).ssh_info()),
-                project.is_via_collab(),
-            )
-        }) else {
-            return Task::ready(Err(anyhow!("Project is not local")));
+        let remote_client = self
+            .workspace
+            .update(cx, |workspace, cx| {
+                let project = workspace.project().read(cx);
+                if project.is_via_collab() {
+                    Err(anyhow!("cannot spawn tasks as a guest"))
+                } else {
+                    Ok(project.remote_client())
+                }
+            })
+            .flatten();
+
+        let remote_client = match remote_client {
+            Ok(remote_client) => remote_client,
+            Err(e) => return Task::ready(Err(e)),
         };
 
-        let builder = ShellBuilder::new(ssh_client.as_ref().map(|info| &*info.shell), &task.shell);
+        let remote_shell = remote_client
+            .as_ref()
+            .and_then(|remote_client| remote_client.read(cx).shell());
+
+        let builder = ShellBuilder::new(remote_shell.as_deref(), &task.shell);
         let command_label = builder.command_label(&task.command_label);
         let (command, args) = builder.build(task.command.clone(), &task.args);