printf: Test formatting hex with padding

tests/by-util/test_printf.rs

@@ -906,6 +906,10 @@ fn pad_unsigned_three() {
         ("%#.3x", "0x003"),
         ("%#.3X", "0X003"),
         ("%#.3o", "003"),
+        ("%#05x", "0x003"),
+        ("%#05X", "0X003"),
+        ("%3x", "  3"),
+        ("%3X", "  3"),
     ] {
         new_ucmd!()
             .args(&[format, "3"])