vim: Copy comment to new lines with o/O (#19766)

Co-Authored-By: Kurt Wolf <kurtwolfbuilds@gmail.com>

Closes: #4691

Closes #ISSUE

Release Notes:

- vim: o/O now respect `extend_comment_on_newline`

crates/multi_buffer/src/multi_buffer.rs

@@ -2862,6 +2862,30 @@ impl MultiBufferSnapshot {
         }
     }
 
+    pub fn indent_and_comment_for_line(&self, row: MultiBufferRow, cx: &AppContext) -> String {
+        let mut indent = self.indent_size_for_line(row).chars().collect::<String>();
+
+        if self.settings_at(0, cx).extend_comment_on_newline {
+            if let Some(language_scope) = self.language_scope_at(Point::new(row.0, 0)) {
+                let delimiters = language_scope.line_comment_prefixes();
+                for delimiter in delimiters {
+                    if *self
+                        .chars_at(Point::new(row.0, indent.len() as u32))
+                        .take(delimiter.chars().count())
+                        .collect::<String>()
+                        .as_str()
+                        == **delimiter
+                    {
+                        indent.push_str(&delimiter);
+                        break;
+                    }
+                }
+            }
+        }
+
+        indent
+    }
+
     pub fn prev_non_blank_row(&self, mut row: MultiBufferRow) -> Option<MultiBufferRow> {
         while row.0 > 0 {
             row.0 -= 1;