ui2: Reorganize components (#3228)

This PR reorganizes the components in the `ui2` crate.

The distinction between "elements" and "components" is now gone, with
all of the reusable components living under `components/`.

The components that we built while prototyping but will eventually live
in other crates currently reside in the `to_extract/` module.

Release Notes:

- N/A

crates/ui2/src/to_extract/toolbar.rs

@@ -0,0 +1,126 @@
+use gpui2::AnyElement;
+use smallvec::SmallVec;
+
+use crate::prelude::*;
+
+#[derive(Clone)]
+pub struct ToolbarItem {}
+
+#[derive(Component)]
+pub struct Toolbar<V: 'static> {
+    left_items: SmallVec<[AnyElement<V>; 2]>,
+    right_items: SmallVec<[AnyElement<V>; 2]>,
+}
+
+impl<V: 'static> Toolbar<V> {
+    pub fn new() -> Self {
+        Self {
+            left_items: SmallVec::new(),
+            right_items: SmallVec::new(),
+        }
+    }
+
+    pub fn left_item(mut self, child: impl Component<V>) -> Self
+    where
+        Self: Sized,
+    {
+        self.left_items.push(child.render());
+        self
+    }
+
+    pub fn left_items(mut self, iter: impl IntoIterator<Item = impl Component<V>>) -> Self
+    where
+        Self: Sized,
+    {
+        self.left_items
+            .extend(iter.into_iter().map(|item| item.render()));
+        self
+    }
+
+    pub fn right_item(mut self, child: impl Component<V>) -> Self
+    where
+        Self: Sized,
+    {
+        self.right_items.push(child.render());
+        self
+    }
+
+    pub fn right_items(mut self, iter: impl IntoIterator<Item = impl Component<V>>) -> Self
+    where
+        Self: Sized,
+    {
+        self.right_items
+            .extend(iter.into_iter().map(|item| item.render()));
+        self
+    }
+
+    fn render(self, _view: &mut V, cx: &mut ViewContext<V>) -> impl Component<V> {
+        div()
+            .bg(cx.theme().colors().toolbar)
+            .p_2()
+            .flex()
+            .justify_between()
+            .child(div().flex().children(self.left_items))
+            .child(div().flex().children(self.right_items))
+    }
+}
+
+#[cfg(feature = "stories")]
+pub use stories::*;
+
+#[cfg(feature = "stories")]
+mod stories {
+    use std::path::PathBuf;
+    use std::str::FromStr;
+
+    use gpui2::{Div, Render};
+
+    use crate::{Breadcrumb, HighlightedText, Icon, IconButton, Story, Symbol};
+
+    use super::*;
+
+    pub struct ToolbarStory;
+
+    impl Render for ToolbarStory {
+        type Element = Div<Self>;
+
+        fn render(&mut self, cx: &mut ViewContext<Self>) -> Self::Element {
+            Story::container(cx)
+                .child(Story::title_for::<_, Toolbar<Self>>(cx))
+                .child(Story::label(cx, "Default"))
+                .child(
+                    Toolbar::new()
+                        .left_item(Breadcrumb::new(
+                            PathBuf::from_str("crates/ui/src/components/toolbar.rs").unwrap(),
+                            vec![
+                                Symbol(vec![
+                                    HighlightedText {
+                                        text: "impl ".to_string(),
+                                        color: cx.theme().syntax_color("keyword"),
+                                    },
+                                    HighlightedText {
+                                        text: "ToolbarStory".to_string(),
+                                        color: cx.theme().syntax_color("function"),
+                                    },
+                                ]),
+                                Symbol(vec![
+                                    HighlightedText {
+                                        text: "fn ".to_string(),
+                                        color: cx.theme().syntax_color("keyword"),
+                                    },
+                                    HighlightedText {
+                                        text: "render".to_string(),
+                                        color: cx.theme().syntax_color("function"),
+                                    },
+                                ]),
+                            ],
+                        ))
+                        .right_items(vec![
+                            IconButton::new("toggle_inlay_hints", Icon::InlayHint),
+                            IconButton::new("buffer_search", Icon::MagnifyingGlass),
+                            IconButton::new("inline_assist", Icon::MagicWand),
+                        ]),
+                )
+        }
+    }
+}