Add tRPC, use it for group expenses, balances and information page (#246)

* Add tRPC, use it for group expense list

* Use tRPC for balances

* Use tRPC in group information + better loading states

src/app/api/trpc/[trpc]/route.ts

@@ -0,0 +1,13 @@
+import { createTRPCContext } from '@/trpc/init'
+import { appRouter } from '@/trpc/routers/_app'
+import { fetchRequestHandler } from '@trpc/server/adapters/fetch'
+
+const handler = (req: Request) =>
+  fetchRequestHandler({
+    endpoint: '/api/trpc',
+    req,
+    router: appRouter,
+    createContext: createTRPCContext,
+  })
+
+export { handler as GET, handler as POST }