component: Add component and component_preview crates to power UI components (#24456)

This PR formalizes design components with the Component and
ComponentPreview traits.

You can open the preview UI with `workspace: open component preview`.

Component previews no longer need to return `Self` allowing for more
complex previews, and previews of components like `ui::Tooltip` that
supplement other components rather than are rendered by default.

`cargo-machete` incorrectly identifies `linkme` as an unused dep on
crates that have components deriving `IntoComponent`, so you may need to
add this to that crate's `Cargo.toml`:

```toml
# cargo-machete doesn't understand that linkme is used in the component macro
[package.metadata.cargo-machete]
ignored = ["linkme"]
```

Release Notes:

- N/A

---------

Co-authored-by: Marshall Bowers <git@maxdeviant.com>

crates/zed/Cargo.toml

@@ -39,6 +39,7 @@ collab_ui.workspace = true
 collections.workspace = true
 command_palette.workspace = true
 command_palette_hooks.workspace = true
+component_preview.workspace = true
 copilot.workspace = true
 db.workspace = true
 diagnostics.workspace = true
@@ -54,8 +55,8 @@ file_icons.workspace = true
 fs.workspace = true
 futures.workspace = true
 git.workspace = true
-git_ui.workspace = true
 git_hosting_providers.workspace = true
+git_ui.workspace = true
 go_to_line.workspace = true
 gpui = { workspace = true, features = ["wayland", "x11", "font-kit"] }
 gpui_tokio.workspace = true

crates/zed/src/main.rs

@@ -490,6 +490,7 @@ fn main() {
         project_panel::init(Assets, cx);
         git_ui::git_panel::init(cx);
         outline_panel::init(Assets, cx);
+        component_preview::init(cx);
         tasks_ui::init(cx);
         snippets_ui::init(cx);
         channel::init(&app_state.client.clone(), app_state.user_store.clone(), cx);