Style collab panel (#3638)

This PR styles the collab panel.

Release Notes:

- N/A

---------

Co-authored-by: Nate Butler <iamnbutler@gmail.com>
Co-authored-by: Marshall Bowers <1486634+maxdeviant@users.noreply.github.com>

crates/ui2/src/components/disclosure.rs

@@ -1,6 +1,7 @@
-use crate::{prelude::*, Color, Icon, IconButton, IconSize};
 use gpui::ClickEvent;
 
+use crate::{prelude::*, Color, Icon, IconButton, IconSize};
+
 #[derive(IntoElement)]
 pub struct Disclosure {
     is_open: bool,