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>

Cargo.toml

@@ -26,6 +26,8 @@ members = [
     "crates/collections",
     "crates/command_palette",
     "crates/command_palette_hooks",
+    "crates/component",
+    "crates/component_preview",
     "crates/context_server",
     "crates/context_server_settings",
     "crates/copilot",
@@ -226,6 +228,8 @@ collab_ui = { path = "crates/collab_ui" }
 collections = { path = "crates/collections" }
 command_palette = { path = "crates/command_palette" }
 command_palette_hooks = { path = "crates/command_palette_hooks" }
+component = { path = "crates/component" }
+component_preview = { path = "crates/component_preview" }
 context_server = { path = "crates/context_server" }
 context_server_settings = { path = "crates/context_server_settings" }
 copilot = { path = "crates/copilot" }
@@ -426,6 +430,7 @@ jupyter-websocket-client = { version = "0.9.0" }
 libc = "0.2"
 libsqlite3-sys = { version = "0.30.1", features = ["bundled"] }
 linkify = "0.10.0"
+linkme = "0.3.31"
 livekit = { git = "https://github.com/zed-industries/livekit-rust-sdks", rev = "811ceae29fabee455f110c56cd66b3f49a7e5003", features = [
     "dispatcher",
     "services-dispatcher",