Move from Zed fonts to IBM Plex (#13596)

Release Notes:

- Changed the default fonts to IBM Plex Sans and IBM Plex Mono. If you'd
like to go back to using Zed Sans/Zed mono you need to
[download](https://github.com/zed-industries/zed-fonts/releases/tag/1.2.0)
them and install them.

crates/storybook/src/storybook.rs

@@ -117,7 +117,7 @@ impl Render for StoryWrapper {
             .flex()
             .flex_col()
             .size_full()
-            .font_family("Zed Mono")
+            .font_family("Zed Plex Mono")
             .child(self.story.clone())
     }
 }