Consider adding a queue data structure to the Spicy runtime library

[bbannier]

We should consider adding a queue data structure to the Spicy runtime library. We currently only provide a vector<T> and users need to implement their own, if implemented in Spicy code likely inefficient implementation.

We should support at least the following API

struct Queue<T> {
  void push(T);
  optional<T> pop();
  uint64 size();
}

[JustinAzoff]

Zeek could use this as well, there's a queue in zeek, but it's implemented in the script layer on top of a table: https://github.com/zeek/zeek/blob/master/scripts/base/utils/queue.zeek