feat: add shared API operation metadata macro

crates/api-macros/tests/ui/anonymous_body.rs

@@ -0,0 +1,11 @@
+use api_macros::api;
+
+pub struct Response;
+
+#[api]
+pub trait AnonymousBody {
+    #[post("/widgets")]
+    async fn create(&self, #[body] request: (u64, u64)) -> Response;
+}
+
+fn main() {}