settings ui: Add numeric steppers to settings UI (#39491)

This PR adds the numeric stepper component to the settings ui and
implements some settings that rely on this component as well.

I also switched {buffer/ui}_font_weight to the `gpui::FontWeight` type
and added a manual implementation of the Schemars trait. This allows Zed
to send min, max, and default information to the JSON LSP when a user is
manually editing the settings file.

The numeric stepper elements added to the settings ui are below:
- ui font size
- ui font weight
- Buffer font size
- Buffer font weight 
- Scroll sensitivity
- Fast scroll sensitivity
- Vertical scroll margin
- Horizontal scroll margin
- Inline blame padding 
- Inline blame delay
- Inline blame min column
- Unnecessary code fade
- Tab Size
- Hover popover delay

Release Notes:

- N/A

Cargo.lock

@@ -14292,6 +14292,7 @@ name = "settings"
 version = "0.1.0"
 dependencies = [
  "anyhow",
+ "derive_more",
  "ec4rs",
  "fs",
  "futures 0.3.31",
@@ -14379,6 +14380,7 @@ dependencies = [
  "strum 0.27.1",
  "theme",
  "ui",
+ "ui_input",
  "workspace",
  "workspace-hack",
  "zed-util",