Moved `grantXxx` methods from `Queue` to `QueueRef`, so they can now be
performed on imported queues.

Added commonly needed permissions to `grantConsumeMessages` and
`grantSendMessages` such as `sqs:GetQueueAttributes`, `sqs:GetQueueUrl`
and the various `sqs:xxxBatch` actions.

Added support for adding arbitrary actions to each of the grant methods.

Exposed `queue.grant(...actions)` as a general purpose grant method
which allows users to customize the set of actions for this specific 
resource/principal pair.

BREAKING CHANGE: `queue.grantReceiveMessages` has been removed. It is unlikely that this would be
sufficient to interact with a queue. Alternatively you can use `queue.grantConsumeMessages` or 
`queue.grant('sqs:ReceiveMessage')` if there's a need to only grant this action.