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

## Background

`itk-dreg` implements a pairwise subimage registration interface in [`itk_dreg.base.registration_interface`](https://github.com/InsightSoftwareConsortium/itk-dreg/blob/main/src/itk_dreg/base/registration_interface.py#L54), 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.