Allow UI font weight to be assigned in settings (#12333)

Release Notes:

- Added the ability to configure the weight of your UI font in standard
CSS weight units from 0 to 900.

crates/gpui/src/text_system.rs

@@ -7,6 +7,8 @@ pub use font_features::*;
 pub use line::*;
 pub use line_layout::*;
 pub use line_wrapper::*;
+use schemars::JsonSchema;
+use serde::{Deserialize, Serialize};
 
 use crate::{
     px, Bounds, DevicePixels, Hsla, Pixels, PlatformTextSystem, Point, Result, SharedString, Size,
@@ -554,7 +556,7 @@ impl DerefMut for LineWrapperHandle {
 
 /// The degree of blackness or stroke thickness of a font. This value ranges from 100.0 to 900.0,
 /// with 400.0 as normal.
-#[derive(Clone, Copy, Debug, PartialEq, PartialOrd)]
+#[derive(Clone, Copy, Debug, PartialEq, PartialOrd, Deserialize, Serialize, JsonSchema)]
 pub struct FontWeight(pub f32);
 
 impl Default for FontWeight {