Builds SimpleElastix Python 3.11 wheels (limited API) with
SimpleITK_USE_ELASTIX enabled. No source archives, no doxygen,
no publishing. Renames output wheels from SimpleITK to SimpleElastix.

Add a package-docker job building manylinux wheels for all four matrix
entries (x86_64 and aarch64, manylinux2014 and manylinux2-28) with
SimpleITK_USE_ELASTIX enabled and Python 3.11 limited API only.
Output wheels are renamed from SimpleITK to SimpleElastix.

Update cmd.sh to conditionally pass -DSimpleITK_USE_ELASTIX:BOOL=ON
to the SuperBuild cmake when the SIMPLEITK_USE_ELASTIX env var is set.
This is backwards-compatible; existing Package.yml builds are
unaffected.

Use CMake 4.2.0 in GHA

Add a CMake cache variable SimpleITK_PYTHON_PACKAGE_NAME (default
"SimpleITK") to allow the Python package to be built under an
alternate name such as SimpleElastix.

- Use the variable for SWIG output directory, install destinations,
  and configured file paths in Wrapping/Python/CMakeLists.txt
- Use lowercase variant in pyproject.toml.in for the PyPI package name
- Switch Python source files to relative imports so they work
  regardless of the package directory name
- Install a SimpleITK compatibility shim into the test virtualenv
  when the package is renamed, so "import SimpleITK" still works

Add a ctest_test_exclude input to the package_python composite action
that allows callers to specify a regex pattern for excluding tests from
ctest_test. When set, the CTEST_TEST_ARGS environment variable is
constructed with EXCLUDE;<pattern> which is passed through
github_actions.cmake to ctest_test() in simpleitk_common.cmake.

Use this in ElastixPackage.yml to exclude Python.Test(ArrayView|
ImageBuffer|Numpy) tests that fail because the package is named
SimpleElastix instead of SimpleITK.