Restructure action macro to assign a namespace to every action

Also, allow arbitrary types to be used as Actions via the impl_actions macro

Co-authored-by: Nathan Sobo <nathan@zed.dev>
Co-authored-by: Keith Simmons <keith@zed.dev>

crates/gpui/src/app/action.rs

@@ -0,0 +1,56 @@
+use std::any::{Any, TypeId};
+
+pub trait Action: 'static {
+    fn id(&self) -> TypeId;
+    fn namespace(&self) -> &'static str;
+    fn name(&self) -> &'static str;
+    fn as_any(&self) -> &dyn Any;
+    fn boxed_clone(&self) -> Box<dyn Action>;
+    fn boxed_clone_as_any(&self) -> Box<dyn Any>;
+}
+
+#[macro_export]
+macro_rules! impl_actions {
+    ($namespace:path, [ $($name:ident),* $(,)? ]) => {
+        $(
+            impl $crate::action::Action for $name {
+                fn id(&self) -> std::any::TypeId {
+                    std::any::TypeId::of::<$name>()
+                }
+
+                fn namespace(&self) -> &'static str {
+                    stringify!($namespace)
+                }
+
+                fn name(&self) -> &'static str {
+                    stringify!($name)
+                }
+
+                fn as_any(&self) -> &dyn std::any::Any {
+                    self
+                }
+
+                fn boxed_clone(&self) -> Box<dyn $crate::action::Action> {
+                    Box::new(self.clone())
+                }
+
+                fn boxed_clone_as_any(&self) -> Box<dyn std::any::Any> {
+                    Box::new(self.clone())
+                }
+            }
+        )*
+    };
+}
+
+#[macro_export]
+macro_rules! actions {
+    ($namespace:path, [ $($name:ident),* $(,)? ]) => {
+
+        $(
+            #[derive(Clone, Debug, Default, PartialEq, Eq)]
+            pub struct $name;
+        )*
+
+        $crate::impl_actions!($namespace, [ $($name),* ]);
+    };
+}