Support DL queue arguments

[mnow-cd]

At this moment there is no way to pass arguments to a DL queue.
For example: all DL queues are a classic type and cannot be changed to a quorum type.

With this change it will be possible.

Examples:

parameters:
  # set default arguments for all DL queues
  with_dl:
    arguments:
      x-queue-type: quorum

queues:
  my-queue:
    # remove all arguments for this queue
    with_dl:
      arguments: []
    # override arguments for this queue
    with_dl:
      arguments:
        x-other-arg: value
    # or disable DL for this queue
    with_dl: false