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/editor/src/display_map/block_map.rs

@@ -1221,7 +1221,7 @@ mod tests {
     use super::*;
     use crate::display_map::inlay_map::InlayMap;
     use crate::display_map::{fold_map::FoldMap, tab_map::TabMap, wrap_map::WrapMap};
-    use gpui::{div, font, px, AssetSource, Element};
+    use gpui::{div, font, px, Element};
     use multi_buffer::MultiBuffer;
     use rand::prelude::*;
     use settings::SettingsStore;
@@ -2014,12 +2014,7 @@ mod tests {
         let settings = SettingsStore::test(cx);
         cx.set_global(settings);
         theme::init(theme::LoadThemes::JustBase, cx);
-        cx.text_system()
-            .add_fonts(vec![assets::Assets
-                .load("fonts/zed-mono/zed-mono-extended.ttf")
-                .unwrap()
-                .unwrap()])
-            .unwrap();
+        assets::Assets.load_test_fonts(cx);
     }
 
     impl TransformBlock {