Pursue ANTs implementation of the `itk-dreg` subimage registration interface

[tbirdso]

Background

itk-dreg implements a pairwise subimage registration interface in itk_dreg.base.registration_interface, with one possible implementation distributed under itk-dreg.elastix. Other implementations may be provided as extensions via other Python wheels.

Feature Request

We should explore a registration implementation based on ANTsPy to complement the ITKElastix implementation.

1. Recommended: create a new repository itk-dreg-ants to implement the Python package.
2. Have itk_dreg_ants depend on itk_dreg in its pyproject.toml file.
3. Implement AntsBlockPairRegistrationMethod that derives from itk_dreg.base.registration_interface.BlockPairRegistrationMethod and returns the forward and inverse results from subimage pairwise registration.
4. Distribute itk-dreg-ants on PyPI with examples and automated tests.