Support SSH usernames which contain @ symbols (#25314)

Closes #25246

Release Notes:

- SSH: Improved handling of multiple `@` in connection strings: e.g.
`ssh jim.lv@es2@10.220.67.57@11.239.1.231` improving support of jump
hosts running JumpServer.

---------

Co-authored-by: Conrad Irwin <conrad.irwin@gmail.com>

crates/remote/Cargo.toml

@@ -39,6 +39,7 @@ shlex.workspace = true
 smol.workspace = true
 tempfile.workspace = true
 thiserror.workspace = true
+urlencoding.workspace = true
 util.workspace = true
 
 [dev-dependencies]

crates/remote/src/ssh_session.rs

@@ -203,7 +203,8 @@ impl SshConnectionOptions {
                 anyhow::bail!("unsupported argument: {:?}", arg);
             }
             let mut input = &arg as &str;
-            if let Some((u, rest)) = input.split_once('@') {
+            // Destination might be: username1@username2@ip2@ip1
+            if let Some((u, rest)) = input.rsplit_once('@') {
                 input = rest;
                 username = Some(u.to_string());
             }
@@ -238,7 +239,9 @@ impl SshConnectionOptions {
     pub fn ssh_url(&self) -> String {
         let mut result = String::from("ssh://");
         if let Some(username) = &self.username {
-            result.push_str(username);
+            // Username might be: username1@username2@ip2
+            let username = urlencoding::encode(username);
+            result.push_str(&username);
             result.push('@');
         }
         result.push_str(&self.host);