[TRI-5835] Add the concurrencyKey to the run ctx

[matt-aitken]

You can trigger a run with a concurrencyKey to create a copy of a queue at runtime. It would be useful if this value would come through to the actual task when it executes (via the ctx).

await myTask.trigger(payload, {
  concurrencyKey: "user-123",
  queue: "user-queue"
});

export const myTask = task({
  id: "my-task",
  run: async (payload, { ctx }) => {
    // We should add ctx.concurrencyKey
    // "user-123"
    ctx.concurrencyKey
  }
});

_TRI-5835

[omkardongre]

Hi! I'd like to work on this issue. I'm currently exploring it and will update my progress here. Could you please assign it to me?