Add support for resizing splits and docks, as well as utilities (#3595)

Making this PR to upstream changes to util and GPUI2, resizing exists
but isn't working yet.

Release Notes:

- N/A

crates/gpui2/src/platform/mac/platform.rs

@@ -49,6 +49,7 @@ use std::{
     rc::Rc,
     slice, str,
     sync::Arc,
+    time::Duration,
 };
 use time::UtcOffset;
 
@@ -657,6 +658,13 @@ impl Platform for MacPlatform {
         "macOS"
     }
 
+    fn double_click_interval(&self) -> Duration {
+        unsafe {
+            let double_click_interval: f64 = msg_send![class!(NSEvent), doubleClickInterval];
+            Duration::from_secs_f64(double_click_interval)
+        }
+    }
+
     fn os_version(&self) -> Result<SemanticVersion> {
         unsafe {
             let process_info = NSProcessInfo::processInfo(nil);

crates/gpui2/src/platform/test/platform.rs

@@ -12,6 +12,7 @@ use std::{
     path::PathBuf,
     rc::{Rc, Weak},
     sync::Arc,
+    time::Duration,
 };
 
 pub struct TestPlatform {
@@ -274,4 +275,8 @@ impl Platform for TestPlatform {
     fn delete_credentials(&self, _url: &str) -> Result<()> {
         Ok(())
     }
+
+    fn double_click_interval(&self) -> std::time::Duration {
+        Duration::from_millis(500)
+    }
 }