Print the binary required by the debug adapter (helix-editor#5195)

This commit addresses issue 5193, where the author
requested that the name of the binary needed is printed along
with the rest of the health information.

This commit adds a format! macro which formats in the name of the
binary and then it will be printed along with the rest of the
debug information. The value in cmd is referenced to the call
to which, and then consumed upon the call to format!

helix-term/src/health.rs

@@ -281,9 +281,9 @@ fn probe_protocol(protocol_name: &str, server_cmd: Option<String>) -> std::io::R
     writeln!(stdout, "Configured {}: {}", protocol_name, cmd_name)?;
 
     if let Some(cmd) = server_cmd {
-        let path = match which::which(cmd) {
+        let path = match which::which(&cmd) {
             Ok(path) => path.display().to_string().green(),
-            Err(_) => "Not found in $PATH".to_string().red(),
+            Err(_) => format!("'{}' not found in $PATH", cmd).red(),
         };
         writeln!(stdout, "Binary for {}: {}", protocol_name, path)?;
     }