gpui: Add Global marker trait (#7095)

This should prevent a class of bugs where one queries the wrong type of
global, which results in oddities at runtime.

Release Notes:

- N/A

---------

Co-authored-by: Marshall <marshall@zed.dev>
Co-authored-by: Marshall Bowers <elliott.codes@gmail.com>

crates/gpui/src/app/model_context.rs

@@ -1,6 +1,6 @@
 use crate::{
     AnyView, AnyWindowHandle, AppContext, AsyncAppContext, Context, Effect, Entity, EntityId,
-    EventEmitter, Model, Subscription, Task, View, WeakModel, WindowContext, WindowHandle,
+    EventEmitter, Global, Model, Subscription, Task, View, WeakModel, WindowContext, WindowHandle,
 };
 use anyhow::Result;
 use derive_more::{Deref, DerefMut};
@@ -193,7 +193,7 @@ impl<'a, T: 'static> ModelContext<'a, T> {
     /// Updates the given global
     pub fn update_global<G, R>(&mut self, f: impl FnOnce(&mut G, &mut Self) -> R) -> R
     where
-        G: 'static,
+        G: Global,
     {
         let mut global = self.app.lease_global::<G>();
         let result = f(&mut global, self);