linux: Respect window_min_size property (#15314)

https://github.com/zed-industries/zed/pull/13126 added the
`window_min_size` property for window creation, but it was only
implemented for macOS. This PR implements the property on Linux as well.

Release Notes:

- N/A

crates/gpui/src/platform.rs

@@ -706,7 +706,6 @@ pub(crate) struct WindowParams {
 
     pub display_id: Option<DisplayId>,
 
-    #[cfg_attr(target_os = "linux", allow(dead_code))]
     pub window_min_size: Option<Size<Pixels>>,
 }