Fix markdown escaping

Closes #29255

Release Notes:

- Improved handling of markdown escape sequences

crates/markdown/src/markdown.rs

@@ -221,7 +221,12 @@ impl Markdown {
             .count();
         if count > 0 {
             let mut output = String::with_capacity(s.len() + count);
+            let mut is_newline = false;
             for c in s.chars() {
+                if is_newline && c == ' ' {
+                    continue;
+                }
+                is_newline = c == '\n';
                 if c == '\n' {
                     output.push('\n')
                 } else if c.is_ascii_punctuation() {
@@ -1722,6 +1727,15 @@ mod tests {
         rendered.text
     }
 
+    #[test]
+    fn test_escape() {
+        assert_eq!(Markdown::escape("hello `world`"), "hello \\`world\\`");
+        assert_eq!(
+            Markdown::escape("hello\n    cool world"),
+            "hello\n\ncool world"
+        );
+    }
+
     #[track_caller]
     fn assert_mappings(rendered: &RenderedText, expected: Vec<Vec<(usize, usize)>>) {
         assert_eq!(rendered.lines.len(), expected.len(), "line count mismatch");