allow creation of cron/queue for non NextJS api folders (e.g. for tRPC)

[boringContributor]

Currently, the SDK only allows the creation of a Queue/Cron by importing the specific NextJS API handler.

Libraries like tRPC have other approaches and we want to align with them.

Possible solution:

import { Queue } from '@serverlessq/core'

const queue = new Queue(...)

const appRouter = trpc
  .router()
  .mutation('createPost', {
    input: z.object({ name: z.string().min(5) }),
    async resolve(req) {
     ...
     queue.enqueue(...)
     ...
    },
  });