Fix artifact URL recording for pip>=23.3.

[jsirois]

When support for Pip 23.3.1 was added in #2276 a latent bug in artifact
URL recording was exposed in cases where the index being used issued
re-directs. Fix up artifact URL recording to grab the primary index URL
and not subsequent re-directs.

Implementing the fix above led to a test failure that revealed another
bug whereby lock file artifact downloads were not respecting the locked
resolve target when it was a foreign platform, which is now fixed.

Finally, fixing the un-patched foreign platform target issue in lock
file artifact downloads revealed that artifact URLs with hashes were not
being taken advantage of in all cases. Now, when there is a version of
an artifact URL seen that contains hashes - the best of those is always
used to prevent needless post-processing to download and hash the
artifact at lock creation time.

Fixes #2414

[jsirois]

Pre fix commits this ran like:

:; tox -epy311-integration -- --devpi -vvsk test_issue_2414 -n0
...
tests/integration/cli/commands/test_issue_2414.py::test_redirects_dont_stomp_original_index_urls[23.2] PASSED
tests/integration/cli/commands/test_issue_2414.py::test_redirects_dont_stomp_original_index_urls[23.3.1] FAILED
...

Which is expected as per the OP in #2414. The failure for the 23.3.1 case looked like:

...
           Full diff:
E           - (ResolvedRequirement(pin=Pin(project_name=ProjectName(raw='wheel', validated=False, normalized='wheel'), version=Version(raw='0.43.0', normalized='0.43')), artifact=PartialArtifact(url=ArtifactURL(raw_url='https://files.pythonhosted.org/packages/7d/cd/d7460c9a869b16c3dd4e1e403cce337df165368c71d6af229a74699622ce/wheel-0.43.0-py3-none-any.whl', download_url='https://files.pythonhosted.org/packages/7d/cd/d7460c9a869b16c3dd4e1e403cce337df165368c71d6af229a74699622ce/wheel-0.43.0-py3-none-any.whl', normalized_url='https://files.pythonhosted.org/packages/7d/cd/d7460c9a869b16c3dd4e1e403cce337df165368c71d6af229a74699622ce/wheel-0.43.0-py3-none-any.whl', scheme='https', path='/packages/7d/cd/d7460c9a869b16c3dd4e1e403cce337df165368c71d6af229a74699622ce/wheel-0.43.0-py3-none-any.whl', fragment_parameters={}, fingerprints=()), fingerprint=None, verified=False), additional_artifacts=(PartialArtifact(url=ArtifactURL(raw_url='https://m.devpi.net/root/pypi/%2Bf/465/ef92c69fa5c5d/wheel-0.43.0.tar.gz', download_url='https://m.devpi.net/root/pypi/%2Bf/465/ef92c69fa5c5d/wheel-0.43.0.tar.gz', normalized_url='https://m.devpi.net/root/pypi/+f/465/ef92c69fa5c5d/wheel-0.43.0.tar.gz', scheme='https', path='/root/pypi/+f/465/ef92c69fa5c5d/wheel-0.43.0.tar.gz', fragment_parameters={}, fingerprints=()), fingerprint=Fingerprint(algorithm='sha256', hash='465ef92c69fa5c5da2d1cf8ac40559a8c940886afcef87dcf14b9470862f1d85'), verified=False),)),)
E           + (ResolvedRequirement(pin=Pin(project_name=ProjectName(raw='wheel', validated=False, normalized='wheel'), version=Version(raw='0.43.0', normalized='0.43')), artifact=PartialArtifact(url=ArtifactURL(raw_url='https://m.devpi.net/root/pypi/%2Bf/55c/570405f142630/wheel-0.43.0-py3-none-any.whl', download_url='https://m.devpi.net/root/pypi/%2Bf/55c/570405f142630/wheel-0.43.0-py3-none-any.whl', normalized_url='https://m.devpi.net/root/pypi/+f/55c/570405f142630/wheel-0.43.0-py3-none-any.whl', scheme='https', path='/root/pypi/+f/55c/570405f142630/wheel-0.43.0-py3-none-any.whl', fragment_parameters={}, fingerprints=()), fingerprint=Fingerprint(algorithm='sha256', hash='55c570405f142630c6b9f72fe09d9b67cf1477fcf543ae5b8dcb1f5b7377da81'), verified=False), additional_artifacts=(PartialArtifact(url=ArtifactURL(raw_url='https://m.devpi.net/root/pypi/%2Bf/465/ef92c69fa5c5d/wheel-0.43.0.tar.gz', download_url='https://m.devpi.net/root/pypi/%2Bf/465/ef92c69fa5c5d/wheel-0.43.0.tar.gz', normalized_url='https://m.devpi.net/root/pypi/+f/465/ef92c69fa5c5d/wheel-0.43.0.tar.gz', scheme='https', path='/root/pypi/+f/465/ef92c69fa5c5d/wheel-0.43.0.tar.gz', fragment_parameters={}, fingerprints=()), fingerprint=Fingerprint(algorithm='sha256', hash='465ef92c69fa5c5da2d1cf8ac40559a8c940886afcef87dcf14b9470862f1d85'), verified=False),)),)

tests/integration/cli/commands/test_issue_2414.py:93: AssertionError
...

Note the whl URLs differed as in the OP in #2414 case with re-directed https://files.pythonhosted.org URLs vs the expected https://m.devpi.net URLs.

[zmanji]

Tests make sense to me so this lgtm.