feat: add rust-script

external/rust-script/tests/scripts/loop-to-prefix.script

@@ -0,0 +1,10 @@
+#!/bin/sh
+set -e -u
+
+echo "First:"
+echo "line1\nline2" | rust-script --loop \
+    "let mut n=0; move |l| {n+=1; println!(\"{:>6}: {}\",n,l.trim_right())}"
+
+echo "Second:"
+echo "line1\nline2" | rust-script --count --loop \
+    "|l,n| println!(\"{:>6}: {}\", n, l.trim_right())"