Replace click LazyFile with a custom type - #716

Heavily inspired by looking at click.utils._LazyFile to see how it
behaves, create a "binary input" type, which acts as a BinaryIO and
otherwise does relatively little. The param type which wraps it is
responsible for attaching it appropriately to the click Context.

- Rename the open handle property to an `open()` method, to ensure that
  it has an `open()` method -- though not part of the target interface,
  this is a common expectation around handling binary streams

- Use ABC `register()` to make sure that the class passes isinstance()
  checks even though it does not subclass/inherit