fixtures: deprecate FixtureDef.has_location and None global fixture visibility

[bluetech]

This PR is stacked on:

• fixtures: use node-based matching in get_scope_package when possible #14565
• fixtures: order fixture override chains by visibility #14566

The first commit deprecates FixtureDef.has_location. With #14566 it is no longer needed, and use of it is probably wrong.

The second commit removes internal use of None global visibility, replaced by Session visibility.

The third commit deprecates global None visibility (extends the nodeid/baseid deprecation).

With this (the non-deprecated parts of) _register_fixture are neat and clean and this readies us to expose a pytest.register_fixture (next commit in the stack).

[RonnyPfannschmidt]

i wonder if this has actual external users and which those are to decide actual removal later

[bluetech]

i wonder if this has actual external users and which those are to decide actual removal later

I looked at my pytest plugin corpus (checkouts of ~700 plugins).

For has_location I found 1 hit:
https://github.com/willemt/pytest-asyncio-cooperative/blob/580309e280093132e919c25c8adb4ecdb59b7e7a/pytest_asyncio_cooperative/fixtures.py#L41-L43.
They will need to update.

For _register_fixture I found 1 hit:
https://github.com/pytest-dev/pytest-bdd/blob/234fdeb230da3cbeae32ec77f2125c2f0ed7e4bd/src/pytest_bdd/compat.py#L29-L33
The nodeid itself is deprecated, but doesn't use None visibility so update should be straightforward.

For parsefactories I found 3 hits:
pytest-describe/src/pytest_describe/plugin.py:105: self.session._fixturemanager.parsefactories(self)
pytest-eucalyptus/pytest_eucalyptus/plugin.py:79: self.session._fixturemanager.parsefactories(self, unittest=True)
These two seem fine (passing a Node).
https://github.com/cielavenir/pytest-session-fixture-globalize/blob/37fb60981c2825e5c465f2c4816708b6e85866be/pytest_session_fixture_globalize/pytest_session_fixture_globalize.py
Will definitely need update, but it wholly replaces parsefactories, which is deep in "unsupported" territory.

Finally, for FixtureDef ctor I found a few hits with a lot of interesting plugins, but these are the relevant ones:
https://github.com/pytest-dev/pytest-bdd/blob/234fdeb230da3cbeae32ec77f2125c2f0ed7e4bd/src/pytest_bdd/compat.py#L54-L61
Only used for pytest<8.1, not relevant.
https://github.com/Flowminder/pytest-airflow/blob/31b1d2ccd3e3f20155a8bb63d02d38578ef7a4ac/pytest_airflow/plugin.py
Repo is archived, I think it's abandoned. Uses a bunch of internal details, probably already broken.
https://github.com/pytest-dev/pytest-factoryboy/blob/76dc1c106fccf6ce3841e93d4198045e128e279a/src/pytest_factoryboy/fixture.py
Does lots of fixture stuff, though I don't see anything that would break.
https://github.com/voronind/pytest-missing-fixtures/blob/c272672900657f275c9b9acf8c724d59d5ea51f5/pytest_missing_fixtures.py#L56-L75
Will need to update for baseid but doesn't use None.