Use IBM Plex Sans / Lilex (#36084)

The Zed Plex fonts were found to violate the OFL by using the word Plex
in the name.

Lilex has better ligatures and box-drawing characters than Zed Plex
Mono, but Zed Plex Sans should be identical
to IBM Plex Sans.

Closes #15542
Closes zed-industries/zed-fonts#31

Release Notes:

- The "Zed Plex Sans" and "Zed Plex Mono" fonts have been replaced with
"IBM Plex Sans" and "Lilex". The old names still work for backward
compatibility. Other than fixing line-drawing characters, and improving
the ligatures, there should be little visual change as the fonts are all
of the same family.
- Introduced ".ZedSans" and ".ZedMono" as aliases to allow us to easily
change the default fonts in the future. These currently default to "IBM
Plex Sans" and "Lilex" respectively.

crates/vim/src/vim.rs

@@ -284,9 +284,7 @@ pub fn init(cx: &mut App) {
             let count = Vim::take_count(cx).unwrap_or(1) as f32;
             Vim::take_forced_motion(cx);
             let theme = ThemeSettings::get_global(cx);
-            let Ok(font_id) = window.text_system().font_id(&theme.buffer_font) else {
-                return;
-            };
+            let font_id = window.text_system().resolve_font(&theme.buffer_font);
             let Ok(width) = window
                 .text_system()
                 .advance(font_id, theme.buffer_font_size(cx), 'm')
@@ -300,9 +298,7 @@ pub fn init(cx: &mut App) {
             let count = Vim::take_count(cx).unwrap_or(1) as f32;
             Vim::take_forced_motion(cx);
             let theme = ThemeSettings::get_global(cx);
-            let Ok(font_id) = window.text_system().font_id(&theme.buffer_font) else {
-                return;
-            };
+            let font_id = window.text_system().resolve_font(&theme.buffer_font);
             let Ok(width) = window
                 .text_system()
                 .advance(font_id, theme.buffer_font_size(cx), 'm')