fix(rest/request_manager): embed URL in the request body (#536)

* fix big brain bot auth on proxy rest

* whoops

* fix header

* fix url and method in body

src/rest/request_manager.ts

@@ -222,8 +222,11 @@ function runMethod(
     !url.startsWith(IMAGE_BASE_URL)
   ) {
     return fetch(url, {
-      method,
-      body: body ? JSON.stringify(body) : undefined,
+      body: JSON.stringify({
+        url,
+        method,
+        ...(body as Record<string, unknown> || {}),
+      }),
       headers: {
         authorization: restAuthorization,
       },