windows: better looking titlebar (#9053)

~~work in progress. not ready for review. made for visibility only, but
feel free to comment :)~~

TODO:
- [x] add close/min/max buttons (to be rendered with gpui)
- [x] snap layout support
- [x] fix issues with clicking items in titlebar
- [x] cleanup/document

Release Notes:

- Added custom windows titlebar

![](https://media.discordapp.net/attachments/1208481909676576818/1216985375969378324/caption-buttons-working.gif?ex=660260f4&is=65efebf4&hm=53a17af6e2f233eba54302a5adb9efe23900f4d6f6d1d854bec887120789130c&=)

---------

Co-authored-by: Mikayla <mikayla@zed.dev>

crates/ui/src/components.rs

@@ -9,6 +9,7 @@ mod indicator;
 mod keybinding;
 mod label;
 mod list;
+mod platform_titlebar;
 mod popover;
 mod popover_menu;
 mod right_click_menu;
@@ -31,6 +32,7 @@ pub use indicator::*;
 pub use keybinding::*;
 pub use label::*;
 pub use list::*;
+pub use platform_titlebar::*;
 pub use popover::*;
 pub use popover_menu::*;
 pub use right_click_menu::*;