Extract auto_update_ui crate (#21008)

This PR extracts an `auto_update_ui` crate out of the `auto_update`
crate.

This allows `auto_update` to not depend on heavier crates like `editor`,
which in turn allows other downstream crates to start building sooner.

Release Notes:

- N/A

crates/auto_update/src/update_notification.rs

@@ -1,68 +0,0 @@
-use gpui::{
-    div, DismissEvent, EventEmitter, InteractiveElement, IntoElement, ParentElement, Render,
-    SemanticVersion, StatefulInteractiveElement, Styled, ViewContext, WeakView,
-};
-use menu::Cancel;
-use release_channel::ReleaseChannel;
-use util::ResultExt;
-use workspace::{
-    ui::{h_flex, v_flex, Icon, IconName, Label, StyledExt},
-    Workspace,
-};
-
-pub struct UpdateNotification {
-    version: SemanticVersion,
-    workspace: WeakView<Workspace>,
-}
-
-impl EventEmitter<DismissEvent> for UpdateNotification {}
-
-impl Render for UpdateNotification {
-    fn render(&mut self, cx: &mut gpui::ViewContext<Self>) -> impl IntoElement {
-        let app_name = ReleaseChannel::global(cx).display_name();
-
-        v_flex()
-            .on_action(cx.listener(UpdateNotification::dismiss))
-            .elevation_3(cx)
-            .p_4()
-            .child(
-                h_flex()
-                    .justify_between()
-                    .child(Label::new(format!(
-                        "Updated to {app_name} {}",
-                        self.version
-                    )))
-                    .child(
-                        div()
-                            .id("cancel")
-                            .child(Icon::new(IconName::Close))
-                            .cursor_pointer()
-                            .on_click(cx.listener(|this, _, cx| this.dismiss(&menu::Cancel, cx))),
-                    ),
-            )
-            .child(
-                div()
-                    .id("notes")
-                    .child(Label::new("View the release notes"))
-                    .cursor_pointer()
-                    .on_click(cx.listener(|this, _, cx| {
-                        this.workspace
-                            .update(cx, |workspace, cx| {
-                                crate::view_release_notes_locally(workspace, cx);
-                            })
-                            .log_err();
-                        this.dismiss(&menu::Cancel, cx)
-                    })),
-            )
-    }
-}
-
-impl UpdateNotification {
-    pub fn new(version: SemanticVersion, workspace: WeakView<Workspace>) -> Self {
-        Self { version, workspace }
-    }
-
-    pub fn dismiss(&mut self, _: &Cancel, cx: &mut ViewContext<Self>) {
-        cx.emit(DismissEvent);
-    }
-}