add version and path to plugin executable help (nushell#13764)

# Description

This change allows one to see the version of their plugin file without
trying to register it.


![image](https://github.com/user-attachments/assets/9f1ddbd7-f63f-47f7-87c8-0d839f5e4b1f)


# User-Facing Changes
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# Tests + Formatting
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> **Note**
> from `nushell` you can also use the `toolkit` as follows
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crates/nu-plugin/src/plugin/mod.rs

@@ -655,6 +655,15 @@ fn print_help(plugin: &impl Plugin, encoder: impl PluginEncoder) {
 
     println!("Nushell Plugin");
     println!("Encoder: {}", encoder.name());
+    println!("Version: {}", plugin.version());
+
+    // Determine the plugin name
+    let exe = std::env::current_exe().ok();
+    let plugin_name: String = exe
+        .as_ref()
+        .map(|stem| stem.to_string_lossy().into_owned())
+        .unwrap_or_else(|| "(unknown)".into());
+    println!("Plugin file path: {}", plugin_name);
 
     let mut help = String::new();
     let help_style = HelpStyle::default();