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/collections/src/collections.rs

@@ -11,13 +11,4 @@ pub type HashMap<K, V> = std::collections::HashMap<K, V>;
 pub type HashSet<T> = std::collections::HashSet<T>;
 
 pub use rustc_hash::{FxHashMap, FxHashSet};
-use std::any::TypeId;
 pub use std::collections::*;
-
-// NEW TYPES
-
-#[derive(Default)]
-pub struct CommandPaletteFilter {
-    pub hidden_namespaces: HashSet<&'static str>,
-    pub hidden_action_types: HashSet<TypeId>,
-}