linux: Update cosmic_text (#13095)

Bumps cosmic_text, removes some stale `todo`s and stores a ShapeBuffer
to prevent reallocations

Improvements:

- Performance should be a lot better (haven't actually tested it)
- Fixed display of `\t` in the terminal

![image](https://github.com/zed-industries/zed/assets/71973804/ca994912-851d-48ef-8dc7-b244c9eb484d)

![image](https://github.com/zed-industries/zed/assets/71973804/42fa9acf-ec10-4247-a5e3-2d4fe664ded6)


Release Notes:

- N/A

crates/gpui/Cargo.toml

@@ -103,7 +103,7 @@ blade-graphics.workspace = true
 blade-macros.workspace = true
 blade-util.workspace = true
 bytemuck = "1"
-cosmic-text = "0.11.2"
+cosmic-text = { git = "https://github.com/pop-os/cosmic-text", rev = "542b20c" }
 copypasta = "0.10.1"
 
 [target.'cfg(target_os = "linux")'.dependencies]