Markdown preview image rendering (#21082)

Closes https://github.com/zed-industries/zed/issues/13246

Supersedes: https://github.com/zed-industries/zed/pull/16192

I couldn't push to the git fork this user was using, so here's the exact
same PR but with some style nits implemented.


Release Notes:

- Added image rendering to the Markdown preview

---------

Co-authored-by: dovakin0007 <dovakin0007@gmail.com>
Co-authored-by: dovakin0007 <73059450+dovakin0007@users.noreply.github.com>

crates/rich_text/src/rich_text.rs

@@ -310,12 +310,7 @@ pub fn render_markdown_mut(
             }
             Event::Start(tag) => match tag {
                 Tag::Paragraph => new_paragraph(text, &mut list_stack),
-                Tag::Heading {
-                    level: _,
-                    id: _,
-                    classes: _,
-                    attrs: _,
-                } => {
+                Tag::Heading { .. } => {
                     new_paragraph(text, &mut list_stack);
                     bold_depth += 1;
                 }
@@ -333,12 +328,7 @@ pub fn render_markdown_mut(
                 Tag::Emphasis => italic_depth += 1,
                 Tag::Strong => bold_depth += 1,
                 Tag::Strikethrough => strikethrough_depth += 1,
-                Tag::Link {
-                    link_type: _,
-                    dest_url,
-                    title: _,
-                    id: _,
-                } => link_url = Some(dest_url.to_string()),
+                Tag::Link { dest_url, .. } => link_url = Some(dest_url.to_string()),
                 Tag::List(number) => {
                     list_stack.push((number, false));
                 }