Workspace persistence for SSH projects (#17996)

TODOs:

- [x] Add tests to `workspace/src/persistence.rs`
- [x] Add a icon for ssh projects
- [x] Fix all `TODO` comments
- [x] Use `port` if it's passed in the ssh connection options

In next PRs:
- Make sure unsaved buffers are persisted/restored, along with other
items/layout
- Handle multiple paths/worktrees correctly


Release Notes:

- N/A

---------

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

crates/remote/src/ssh_session.rs

@@ -33,6 +33,11 @@ use std::{
 };
 use tempfile::TempDir;
 
+#[derive(
+    Debug, PartialEq, Eq, PartialOrd, Ord, Hash, Clone, Copy, serde::Serialize, serde::Deserialize,
+)]
+pub struct SshProjectId(pub u64);
+
 #[derive(Clone)]
 pub struct SshSocket {
     connection_options: SshConnectionOptions,