Rename IconElement to just Icon (#3974)

This PR renames the `IconElement` component to just `Icon`.

This better matches the rest of our components, as `IconElement` was the
only one using this naming convention.

The `Icon` enum has been renamed to `IconName` to free up the name.

I was trying to come up with a way that would allow rendering an
`Icon::Zed` directly (and thus make the `IconElement` a hidden part of
the API), but I couldn't come up with a way to do this cleanly.

Release Notes:

- N/A

crates/ui/src/components/context_menu.rs

@@ -1,6 +1,6 @@
 use crate::{
-    h_stack, prelude::*, v_stack, Icon, IconElement, KeyBinding, Label, List, ListItem,
-    ListSeparator, ListSubHeader,
+    h_stack, prelude::*, v_stack, Icon, IconName, KeyBinding, Label, List, ListItem, ListSeparator,
+    ListSubHeader,
 };
 use gpui::{
     px, Action, AnyElement, AppContext, DismissEvent, EventEmitter, FocusHandle, FocusableView,
@@ -14,7 +14,7 @@ enum ContextMenuItem {
     Header(SharedString),
     Entry {
         label: SharedString,
-        icon: Option<Icon>,
+        icon: Option<IconName>,
         handler: Rc<dyn Fn(&mut WindowContext)>,
         action: Option<Box<dyn Action>>,
     },
@@ -117,7 +117,7 @@ impl ContextMenu {
             label: label.into(),
             action: Some(action.boxed_clone()),
             handler: Rc::new(move |cx| cx.dispatch_action(action.boxed_clone())),
-            icon: Some(Icon::Link),
+            icon: Some(IconName::Link),
         });
         self
     }
@@ -280,7 +280,7 @@ impl Render for ContextMenu {
                                 h_stack()
                                     .gap_1()
                                     .child(Label::new(label.clone()))
-                                    .child(IconElement::new(*icon))
+                                    .child(Icon::new(*icon))
                                     .into_any_element()
                             } else {
                                 Label::new(label.clone()).into_any_element()