fix some edge cases around multiline attributes

packages/autofmt/src/element.rs

@@ -216,7 +216,26 @@ impl Writer<'_> {
             }
             ElementAttr::AttrExpression { name, value } => {
                 let out = prettyplease::unparse_expr(value);
-                write!(self.out, "{name}: {out}")?;
+                let mut lines = out.split('\n').peekable();
+                let first = lines.next().unwrap();
+
+                // a one-liner for whatever reason
+                // Does not need a new line
+                if lines.peek().is_none() {
+                    write!(self.out, "{name}: {first}")?;
+                } else {
+                    writeln!(self.out, "{name}: {first}")?;
+
+                    while let Some(line) = lines.next() {
+                        self.out.indented_tab()?;
+                        write!(self.out, "{line}")?;
+                        if lines.peek().is_none() {
+                            write!(self.out, "")?;
+                        } else {
+                            writeln!(self.out)?;
+                        }
+                    }
+                }
             }
 
             ElementAttr::CustomAttrText { name, value } => {