Revert "windows: better looking titlebar" and follow-up (#9392)

This reverts #9053 and #9375 because they introduced a regression on
`main` that broke the titlebars on macOS:


![image](https://github.com/zed-industries/zed/assets/1185253/d046003b-5c66-4a42-9385-623f5d58c9a4)

Two things are off:

- Left padding is missing
- Titlebar height is less than it was before, which means the
traffic-light buttons are not centered vertically

What @as-cii and I noticed while looking into this: the `cfg!(macos)`
macros that were used don't work like that. You need to check for
`cfg!(target = "macos")` etc. Means that on macOS we never used the
macOS-specific code because the condition was always false.

Overall height, we're not sure about.

Release Notes:

- N/A

crates/gpui/src/platform/test/window.rs

@@ -1,7 +1,7 @@
 use crate::{
-    AnyWindowHandle, AtlasKey, AtlasTextureId, AtlasTile, Bounds, DispatchEventResult,
-    GlobalPixels, Pixels, PlatformAtlas, PlatformDisplay, PlatformInput, PlatformInputHandler,
-    PlatformWindow, Point, Size, TestPlatform, TileId, WindowAppearance, WindowParams,
+    AnyWindowHandle, AtlasKey, AtlasTextureId, AtlasTile, Bounds, GlobalPixels, Pixels,
+    PlatformAtlas, PlatformDisplay, PlatformInput, PlatformInputHandler, PlatformWindow, Point,
+    Size, TestPlatform, TileId, WindowAppearance, WindowParams,
 };
 use collections::HashMap;
 use parking_lot::Mutex;
@@ -20,7 +20,7 @@ pub(crate) struct TestWindowState {
     platform: Weak<TestPlatform>,
     sprite_atlas: Arc<dyn PlatformAtlas>,
     pub(crate) should_close_handler: Option<Box<dyn FnMut() -> bool>>,
-    input_callback: Option<Box<dyn FnMut(PlatformInput) -> DispatchEventResult>>,
+    input_callback: Option<Box<dyn FnMut(PlatformInput) -> bool>>,
     active_status_change_callback: Option<Box<dyn FnMut(bool)>>,
     resize_callback: Option<Box<dyn FnMut(Size<Pixels>, f32)>>,
     moved_callback: Option<Box<dyn FnMut()>>,
@@ -102,7 +102,7 @@ impl TestWindow {
         drop(lock);
         let result = callback(event);
         self.0.lock().input_callback = Some(callback);
-        !result.propagate
+        result
     }
 }
 
@@ -111,10 +111,6 @@ impl PlatformWindow for TestWindow {
         self.0.lock().bounds
     }
 
-    fn is_maximized(&self) -> bool {
-        unimplemented!()
-    }
-
     fn content_size(&self) -> Size<Pixels> {
         self.bounds().size.into()
     }
@@ -124,7 +120,7 @@ impl PlatformWindow for TestWindow {
     }
 
     fn titlebar_height(&self) -> Pixels {
-        32.0.into()
+        unimplemented!()
     }
 
     fn appearance(&self) -> WindowAppearance {
@@ -212,7 +208,7 @@ impl PlatformWindow for TestWindow {
 
     fn on_request_frame(&self, _callback: Box<dyn FnMut()>) {}
 
-    fn on_input(&self, callback: Box<dyn FnMut(crate::PlatformInput) -> DispatchEventResult>) {
+    fn on_input(&self, callback: Box<dyn FnMut(crate::PlatformInput) -> bool>) {
         self.0.lock().input_callback = Some(callback)
     }