Properly format characters with escape sequences

Ran into this just now

crates/compiler/fmt/src/expr.rs

@@ -288,8 +288,17 @@ impl<'a> Formattable for Expr<'a> {
                 buf.push_str(string)
             }
             SingleQuote(string) => {
+                buf.indent(indent);
                 buf.push('\'');
-                buf.push_str(string);
+                for c in string.chars() {
+                    if c == '"' {
+                        buf.push_char_literal('"')
+                    } else {
+                        for escaped in c.escape_default() {
+                            buf.push_char_literal(escaped);
+                        }
+                    }
+                }
                 buf.push('\'');
             }
             &NonBase10Int {

crates/compiler/fmt/src/lib.rs

@@ -86,6 +86,12 @@ impl<'a> Buf<'a> {
         self.text.push_str(s);
     }
 
+    pub fn push_char_literal(&mut self, c: char) {
+        self.flush_spaces();
+
+        self.text.push(c);
+    }
+
     pub fn spaces(&mut self, count: usize) {
         self.spaces_to_flush += count;
     }

crates/compiler/fmt/tests/test_fmt.rs

@@ -5567,6 +5567,21 @@ mod test_fmt {
         );
     }
 
+    #[test]
+    fn format_chars() {
+        expr_formats_same(indoc!(
+            r#"
+            ' '
+            "#
+        ));
+
+        expr_formats_same(indoc!(
+            r#"
+            '\n'
+            "#
+        ));
+    }
+
     // this is a parse error atm
     //    #[test]
     //    fn multiline_apply() {