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.lock

@@ -2942,6 +2942,28 @@ dependencies = [
  "gpui",
 ]
 
+[[package]]
+name = "component"
+version = "0.1.0"
+dependencies = [
+ "collections",
+ "gpui",
+ "linkme",
+ "once_cell",
+ "parking_lot",
+ "theme",
+]
+
+[[package]]
+name = "component_preview"
+version = "0.1.0"
+dependencies = [
+ "component",
+ "gpui",
+ "ui",
+ "workspace",
+]
+
 [[package]]
 name = "concurrent-queue"
 version = "2.5.0"
@@ -7280,6 +7302,26 @@ dependencies = [
  "memchr",
 ]
 
+[[package]]
+name = "linkme"
+version = "0.3.31"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "566336154b9e58a4f055f6dd4cbab62c7dc0826ce3c0a04e63b2d2ecd784cdae"
+dependencies = [
+ "linkme-impl",
+]
+
+[[package]]
+name = "linkme-impl"
+version = "0.3.31"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "edbe595006d355eaf9ae11db92707d4338cd2384d16866131cc1afdbdd35d8d9"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn 2.0.90",
+]
+
 [[package]]
 name = "linux-raw-sys"
 version = "0.4.14"
@@ -8693,9 +8735,9 @@ dependencies = [
 
 [[package]]
 name = "once_cell"
-version = "1.20.2"
+version = "1.20.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "1261fe7e33c73b354eab43b1273a57c8f967d0391e80353e51f764ac02cf6775"
+checksum = "945462a4b81e43c4e3ba96bd7b49d834c6f61198356aa858733bc4acf3cbe62e"
 
 [[package]]
 name = "oo7"
@@ -14320,8 +14362,10 @@ name = "ui"
 version = "0.1.0"
 dependencies = [
  "chrono",
+ "component",
  "gpui",
  "itertools 0.14.0",
+ "linkme",
  "menu",
  "serde",
  "settings",
@@ -14349,6 +14393,7 @@ name = "ui_macros"
 version = "0.1.0"
 dependencies = [
  "convert_case 0.7.1",
+ "linkme",
  "proc-macro2",
  "quote",
  "syn 1.0.109",
@@ -16120,6 +16165,7 @@ dependencies = [
  "client",
  "clock",
  "collections",
+ "component",
  "db",
  "derive_more",
  "env_logger 0.11.6",
@@ -16554,6 +16600,7 @@ dependencies = [
  "collections",
  "command_palette",
  "command_palette_hooks",
+ "component_preview",
  "copilot",
  "db",
  "diagnostics",