windows: Fix and simplify title bar padding (#13420)

This PR fixes the off by one pixel of the top client rect when not
maximized due to the added border. It also simplifies and properly fixes
the title bar padding problem when maximized, it is now properly taken
care of in GPUI rather then adding the padding in the UI.

Release Notes:

- N/A

crates/gpui/src/platform/windows/events.rs

@@ -659,6 +659,13 @@ fn handle_calc_client_size(
     requested_client_rect[0].left += frame_x + padding;
     requested_client_rect[0].bottom -= frame_y + padding;
 
+    if state_ptr.state.borrow().is_maximized() {
+        requested_client_rect[0].top += frame_y + padding;
+    } else {
+        // Magic number that calculates the width of the border
+        requested_client_rect[0].top += frame_y - 3;
+    }
+
     Some(0)
 }
 
@@ -821,14 +828,14 @@ fn handle_hit_test_msg(
 
     let dpi = unsafe { GetDpiForWindow(handle) };
     let frame_y = unsafe { GetSystemMetricsForDpi(SM_CYFRAME, dpi) };
-    let padding = unsafe { GetSystemMetricsForDpi(SM_CXPADDEDBORDER, dpi) };
 
     let mut cursor_point = POINT {
         x: lparam.signed_loword().into(),
         y: lparam.signed_hiword().into(),
     };
     unsafe { ScreenToClient(handle, &mut cursor_point).ok().log_err() };
-    if cursor_point.y > 0 && cursor_point.y < frame_y + padding {
+    if !state_ptr.state.borrow().is_maximized() && cursor_point.y >= 0 && cursor_point.y <= frame_y
+    {
         return Some(HTTOP as _);
     }