Mainline GPUI2 UI work (#3099)

This PR mainlines the current state of new GPUI2-based UI from the
`gpui2-ui` branch.

Included in this is a performance improvement to make use of the
`TextLayoutCache` when calling `layout` for `Text` elements.

Release Notes:

- N/A

---------

Co-authored-by: Nate Butler <iamnbutler@gmail.com>
Co-authored-by: Antonio Scandurra <me@as-cii.com>

crates/storybook/src/stories/components.rs

@@ -6,13 +6,17 @@ pub mod collab_panel;
 pub mod context_menu;
 pub mod facepile;
 pub mod keybinding;
+pub mod language_selector;
+pub mod multi_buffer;
 pub mod palette;
 pub mod panel;
 pub mod project_panel;
+pub mod recent_projects;
 pub mod status_bar;
 pub mod tab;
 pub mod tab_bar;
 pub mod terminal;
+pub mod theme_selector;
 pub mod title_bar;
 pub mod toolbar;
 pub mod traffic_lights;

crates/storybook/src/stories/components/language_selector.rs

@@ -0,0 +1,16 @@
+use ui::prelude::*;
+use ui::LanguageSelector;
+
+use crate::story::Story;
+
+#[derive(Element, Default)]
+pub struct LanguageSelectorStory {}
+
+impl LanguageSelectorStory {
+    fn render<V: 'static>(&mut self, _: &mut V, cx: &mut ViewContext<V>) -> impl IntoElement<V> {
+        Story::container(cx)
+            .child(Story::title_for::<_, LanguageSelector>(cx))
+            .child(Story::label(cx, "Default"))
+            .child(LanguageSelector::new())
+    }
+}

crates/storybook/src/stories/components/multi_buffer.rs

@@ -0,0 +1,24 @@
+use ui::prelude::*;
+use ui::{hello_world_rust_buffer_example, MultiBuffer};
+
+use crate::story::Story;
+
+#[derive(Element, Default)]
+pub struct MultiBufferStory {}
+
+impl MultiBufferStory {
+    fn render<V: 'static>(&mut self, _: &mut V, cx: &mut ViewContext<V>) -> impl IntoElement<V> {
+        let theme = theme(cx);
+
+        Story::container(cx)
+            .child(Story::title_for::<_, MultiBuffer<V>>(cx))
+            .child(Story::label(cx, "Default"))
+            .child(MultiBuffer::new(vec![
+                hello_world_rust_buffer_example(&theme),
+                hello_world_rust_buffer_example(&theme),
+                hello_world_rust_buffer_example(&theme),
+                hello_world_rust_buffer_example(&theme),
+                hello_world_rust_buffer_example(&theme),
+            ]))
+    }
+}

crates/storybook/src/stories/components/recent_projects.rs

@@ -0,0 +1,16 @@
+use ui::prelude::*;
+use ui::RecentProjects;
+
+use crate::story::Story;
+
+#[derive(Element, Default)]
+pub struct RecentProjectsStory {}
+
+impl RecentProjectsStory {
+    fn render<V: 'static>(&mut self, _: &mut V, cx: &mut ViewContext<V>) -> impl IntoElement<V> {
+        Story::container(cx)
+            .child(Story::title_for::<_, RecentProjects>(cx))
+            .child(Story::label(cx, "Default"))
+            .child(RecentProjects::new())
+    }
+}

crates/storybook/src/stories/components/theme_selector.rs

@@ -0,0 +1,16 @@
+use ui::prelude::*;
+use ui::ThemeSelector;
+
+use crate::story::Story;
+
+#[derive(Element, Default)]
+pub struct ThemeSelectorStory {}
+
+impl ThemeSelectorStory {
+    fn render<V: 'static>(&mut self, _: &mut V, cx: &mut ViewContext<V>) -> impl IntoElement<V> {
+        Story::container(cx)
+            .child(Story::title_for::<_, ThemeSelector>(cx))
+            .child(Story::label(cx, "Default"))
+            .child(ThemeSelector::new())
+    }
+}

crates/storybook/src/story_selector.rs

@@ -42,13 +42,17 @@ pub enum ComponentStory {
     CollabPanel,
     Facepile,
     Keybinding,
+    LanguageSelector,
+    MultiBuffer,
     Palette,
     Panel,
     ProjectPanel,
+    RecentProjects,
     StatusBar,
     Tab,
     TabBar,
     Terminal,
+    ThemeSelector,
     TitleBar,
     Toolbar,
     TrafficLights,
@@ -69,15 +73,25 @@ impl ComponentStory {
             Self::CollabPanel => components::collab_panel::CollabPanelStory::default().into_any(),
             Self::Facepile => components::facepile::FacepileStory::default().into_any(),
             Self::Keybinding => components::keybinding::KeybindingStory::default().into_any(),
+            Self::LanguageSelector => {
+                components::language_selector::LanguageSelectorStory::default().into_any()
+            }
+            Self::MultiBuffer => components::multi_buffer::MultiBufferStory::default().into_any(),
             Self::Palette => components::palette::PaletteStory::default().into_any(),
             Self::Panel => components::panel::PanelStory::default().into_any(),
             Self::ProjectPanel => {
                 components::project_panel::ProjectPanelStory::default().into_any()
             }
+            Self::RecentProjects => {
+                components::recent_projects::RecentProjectsStory::default().into_any()
+            }
             Self::StatusBar => components::status_bar::StatusBarStory::default().into_any(),
             Self::Tab => components::tab::TabStory::default().into_any(),
             Self::TabBar => components::tab_bar::TabBarStory::default().into_any(),
             Self::Terminal => components::terminal::TerminalStory::default().into_any(),
+            Self::ThemeSelector => {
+                components::theme_selector::ThemeSelectorStory::default().into_any()
+            }
             Self::TitleBar => components::title_bar::TitleBarStory::default().into_any(),
             Self::Toolbar => components::toolbar::ToolbarStory::default().into_any(),
             Self::TrafficLights => {