Move old plugins (#4721)

crates/old/nu_plugin_start/src/nu/mod.rs

@@ -0,0 +1,28 @@
+use nu_errors::ShellError;
+use nu_plugin::Plugin;
+use nu_protocol::{CallInfo, ReturnValue, Signature, SyntaxShape};
+
+use crate::start::Start;
+
+impl Plugin for Start {
+    fn config(&mut self) -> Result<Signature, ShellError> {
+        Ok(Signature::build("start")
+            .desc("Opens each file/directory/URL using the default application")
+            .rest(
+                "rest",
+                SyntaxShape::String,
+                "files/urls/directories to open",
+            )
+            .named(
+                "application",
+                SyntaxShape::String,
+                "Specifies the application used for opening the files/directories/urls",
+                Some('a'),
+            )
+            .filter())
+    }
+    fn begin_filter(&mut self, call_info: CallInfo) -> Result<Vec<ReturnValue>, ShellError> {
+        self.parse(call_info)?;
+        self.exec().map(|_| Vec::new())
+    }
+}