add containers variable to the input list

[akaiypova]

Hi! Would it be possible to add containers variable to the list of inputs for this module?

variable "containers" {
  type        = list(any)
  description = "Container definitions to use for the task. If this is used, all other container options will be ignored."
  default     = []
}

I would like to be able pass in multiple container to the task definitions module.

[JaredDarling]

See #107