Strip extras marker from 'No matching distribution found' error

[gcomneno]

Fixes #13618.

When a requirement includes an environment marker like ; extra == "...", the final DistributionNotFound message currently shows the marker (e.g. torch; extra == "optimizer"). This change keeps the error focused on the project name only.

Changes (minimal):

• package_finder: use name instead of req in DistributionNotFound
• resolvelib factory: use req.project_name instead of req in DistributionNotFound

Tests:

• python -m pytest -q tests/unit/test_finder.py tests/unit/resolution_resolvelib/

[gcomneno]

Note: running the full test suite locally stops at collection due to missing optional test dependencies (tomli_w/proxy/freezegun). The targeted unit tests covering the touched paths pass: �[32m.�[0m�[32m.�[0m�[32m.�[0m�[32m.�[0m�[32m.�[0m�[32m.�[0m�[32m.�[0m�[32m.�[0m�[32m.�[0m�[32m.�[0m�[32m.�[0m�[32m.�[0m�[32m.�[0m�[32m.�[0m�[32m.�[0m�[32m.�[0m�[32m.�[0m�[32m.�[0m�[32m.�[0m�[32m.�[0m�[32m.�[0m�[32m.�[0m�[32m.�[0m�[32m.�[0m�[32m.�[0m�[32m.�[0m�[32m.�[0m�[32m.�[0m�[32m.�[0m�[32m.�[0m�[32m.�[0m�[32m.�[0m�[32m.�[0m�[32m.�[0m�[32m.�[0m�[32m.�[0m�[32m.�[0m�[32m.�[0m�[32m.�[0m�[32m.�[0m�[32m.�[0m�[32m.�[0m�[32m.�[0m�[32m.�[0m�[32m.�[0m�[32m.�[0m�[32m.�[0m�[32m.�[0m�[32m.�[0m�[32m.�[0m�[32m.�[0m�[32m.�[0m�[32m.�[0m�[32m.�[0m�[32m.�[0m�[32m.�[0m�[32m.�[0m�[32m.�[0m�[32m.�[0m�[32m.�[0m�[32m.�[0m�[32m.�[0m�[32m.�[0m�[32m.�[0m�[32m.�[0m�[32m.�[0m�[32m.�[0m�[32m.�[0m�[32m.�[0m�[32m.�[0m�[32m.�[0m�[32m.�[0m�[32m [ 98%]
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[sepehr-rs]

Hi, this is already covered by an existing PR: #13659