BUG: Replace distutils.version with a standard-library comparison

[hjmjohnson]

Python 3.12 removed distutils, which ten examples imported to check ITK's
version. Compare the dotted components as a tuple instead, dropping the
import entirely.

The failure

Every affected example guards its minimum ITK version like this:

from distutils.version import StrictVersion as VS

if VS(itk.Version.GetITKVersion()) < VS("4.9.0"):
    print("ITK 4.9.0 is required.")
    sys.exit(1)

On Python 3.12 and newer the import raises before the example runs:

Traceback (most recent call last):
ModuleNotFoundError: No module named 'distutils'

The replacement keeps each example's own minimum and drops the import:

if tuple(int(v) for v in itk.Version.GetITKVersion().split(".")) < (4, 9, 0):

Also fixed: a latent NameError in the same guard

SegmentBloodVessels and SegmentBloodVesselsWithMultiScaleHessianBasedMeasure call sys.exit() in that block without importing sys, so on an older ITK they would raise NameError instead of printing the message. Both now import it.

Verification

Built against ITK main with Python 3.14.6 and run through the project's own ctest Python suite:

	before	after
Python tests failing	10	2

All eight distutils casualties pass. The two remaining failures are unrelated to this change and were failing beforehand: ConvolveImageWithKernelTestPython needs matplotlib, which is absent from that environment, and ComputeFFTInOneDimensionPhaseBaselineComparisonPython fails a baseline image comparison (ImageError 25.13, 4 pixels).

pre-commit run --all-files passes, and no distutils reference remains in the repository.