add ui::Vector and separate images from icons (#17815)

This PR pulls non-icon assets out of `ui::components::icon` in
preparation for icon standardization.

In the future icons will have standard names and sizes, and these image
assets won't conform to those constraints.

We can also add a `ui::components::image::Image` wrapper around the
`gpui::img` element in the future for any Zed-specific image styling we
want to enforce.

Of note:

```rust
#[derive(Debug, PartialEq, Eq, Copy, Clone, EnumIter, EnumString, IntoStaticStr, Serialize, Deserialize, DerivePathStr)]
#[strum(serialize_all = "snake_case")]
#[path_str(prefix = "images", suffix = ".svg")]
pub enum VectorName {
    ZedLogo,
    ZedXCopilot,
}
```

You can see in the above code we no longer need to manually specify
paths for image/icon enums like we currently do in
`ui::components::icon`.

The icon component will get this same treatment in the future, once we:

- do the design work needed to standardize the icons
- remove unused icons
- update icon names

Release Notes:

- N/A

crates/gpui_macros/src/gpui_macros.rs

@@ -1,4 +1,5 @@
 mod derive_into_element;
+mod derive_path_static_str;
 mod derive_render;
 mod register_action;
 mod styles;
@@ -27,6 +28,12 @@ pub fn derive_render(input: TokenStream) -> TokenStream {
     derive_render::derive_render(input)
 }
 
+#[proc_macro_derive(PathStaticStr)]
+#[doc(hidden)]
+pub fn derive_path_static_str(input: TokenStream) -> TokenStream {
+    derive_path_static_str::derive_path_static_str(input)
+}
+
 /// Used by GPUI to generate the style helpers.
 #[proc_macro]
 #[doc(hidden)]