Fix fixture visibility with doctest module collection

[bubaizhanshen]

Summary

• include the fixture visibility scope in parsefactories() duplicate tracking
• allow the same module object to be parsed separately for DoctestModule and Module collectors
• add a regression test for --doctest-modules hiding fixtures from normal tests

Fixes #14533

Tests

• PYTHONPATH=/tmp/stubreadline /tmp/pytest-venv/bin/python -m pytest -o minversion=0 testing/test_doctest.py -q
• PYTHONPATH=/tmp/stubreadline /tmp/pytest-venv/bin/python -m pytest -o minversion=0 testing/python/fixtures.py::TestFixtureManagerParseFactories testing/deprecated_test.py::TestFixtureNodeidDeprecations -q
• PYTHONPATH=/tmp/stubreadline /tmp/pytest-venv/bin/python -m ruff check src/_pytest/fixtures.py testing/test_doctest.py
• PYTHONPATH=/tmp/stubreadline /tmp/pytest-venv/bin/python -m ruff format --check src/_pytest/fixtures.py testing/test_doctest.py
• PYTHONPATH=/tmp/stubreadline /tmp/pytest-venv/bin/python -m py_compile src/_pytest/fixtures.py testing/test_doctest.py && git diff --check

[bluetech]

Thanks but there's an open PR #14540 for this issue