Add emergency hotfix for rejected connections to lemmy.world (#100)

Background:

Yesterday, reverse proxied requests on lemmy.app started being
rejected from wefwef.app due to rate limiting built into lemmy
on lemmy.world.

lemmy.world will shortly enable CORS.

Note: This hotfix may only be deployed to wefwef.app.

Future versions of lemmy will enable CORS * by default like
Mastodon, which will completely resolve this issue.

src/services/lemmy.ts

@@ -1,6 +1,10 @@
 import { LemmyHttp } from "lemmy-js-client";
 
 function buildBaseUrl(url: string): string {
+  if (url === "lemmy.world") {
+    return `https://lemmy.world`;
+  }
+
   return `${location.origin}/api/${url}`;
 }