ui: Refine TitleBar component (#9415)

This PR continues the refinements to the `TitleBar` component.

Here are the notable changes:

- `KeyBindingDisplay` and `PlatformStyle` have been unified into a
single `PlatformStyle`.
- This provides us a consistent way for adapting UI to different
platform styles.
- `PlatformTitlebar` has been renamed to `TitleBar`.
  - The `Platform` prefix was irrelevant.
- The Windows window controls have been factored out into a separate
module and have been componentized.

<img width="1283" alt="Screenshot 2024-03-15 at 3 34 38 PM"
src="https://github.com/zed-industries/zed/assets/1486634/07da391f-828b-48bf-8849-58863f4ccce7">

> I'm missing the Segoe Fluent Icons font, so that's why the aren't
rendering properly.

Release Notes:

- N/A

crates/storybook/src/story_selector.rs

@@ -29,10 +29,10 @@ pub enum ComponentStory {
     ListHeader,
     ListItem,
     OverflowScroll,
-    PlatformTitlebar,
     Scroll,
     Tab,
     TabBar,
+    TitleBar,
     ToggleButton,
     Text,
     ViewportUnits,
@@ -61,11 +61,11 @@ impl ComponentStory {
             Self::ListHeader => cx.new_view(|_| ui::ListHeaderStory).into(),
             Self::ListItem => cx.new_view(|_| ui::ListItemStory).into(),
             Self::OverflowScroll => cx.new_view(|_| crate::stories::OverflowScrollStory).into(),
-            Self::PlatformTitlebar => cx.new_view(|_| ui::PlatformTitlebarStory).into(),
             Self::Scroll => ScrollStory::view(cx).into(),
             Self::Text => TextStory::view(cx).into(),
             Self::Tab => cx.new_view(|_| ui::TabStory).into(),
             Self::TabBar => cx.new_view(|_| ui::TabBarStory).into(),
+            Self::TitleBar => cx.new_view(|_| ui::TitleBarStory).into(),
             Self::ToggleButton => cx.new_view(|_| ui::ToggleButtonStory).into(),
             Self::ViewportUnits => cx.new_view(|_| crate::stories::ViewportUnitsStory).into(),
             Self::Picker => PickerStory::new(cx).into(),