Remove e?println macros

These macros are problematic because:
- They panic when the output stream is closed.
- They are not aware of fish's encoding of arbitrary bytes into a section of a
  Unicode private use area. The custom printf macros handle this.

https://github.com/fish-shell/fish-shell/pull/11397
https://github.com/fish-shell/fish-shell/pull/11402

printf/src/arg.rs

@@ -139,6 +139,12 @@ fn to_arg(self) -> Arg<'a> {
     }
 }
 
+impl<'a> ToArg<'a> for &'a std::io::Error {
+    fn to_arg(self) -> Arg<'a> {
+        Arg::String(self.to_string())
+    }
+}
+
 impl<'a> ToArg<'a> for f32 {
     fn to_arg(self) -> Arg<'a> {
         Arg::Float(self.into())