Handle explicit intersphinx inventory names in all domains
Intersphinx supports explicitly specifying the inventory name in a link target, e.g. the python: part in :ref:`python:datetime-datetime` .
The custom missing_reference hook in hoverxref handles such target names as well, but only in the std domain (as far as I can tell, particularly for :ref:, which is in the std domain).
Intersphinx supports target names with explicit inventories regardless of role/domain, which means :py:attr:`python:datetime.time.minute` results in the correct link, but without the hoverxref popup as the python: prefix isn't handled by hoverxref in this case.
This PR attempts to fix this by removing the check for the std domain, which I believe intersphinx also doesn't check.
I'm very much not sure if this makes sense with how Sphinx, Intersphinx and sphinx-hoverxref interact, or if there are side-effects, I don't know a whole lot about Sphinx internals :sweat_smile: Nevertheless, this fixes the aforementioned issue, and tests pass fine :)
The difference between sphinx-hoverxref 1.1.3 and this PR can be seen here:
- https://sphinx-test-stuff.readthedocs.io/en/hoverxref-intersphinx/
- https://sphinx-test-stuff.readthedocs.io/en/hoverxref-intersphinx-fixed/
Note the difference on the second :attr: link, while hovering over the second :ref: link works in both versions.
:books: Documentation preview :books:: https://sphinx-hoverxref--236.org.readthedocs.build/en/236/
:books: Documentation preview :books:: https://read-the-docs-sphinx-hoverxref--236.com.readthedocs.build/en/236/