Handle explicit intersphinx inventory names in all domains

[shiftinv]

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.

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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 1.2.0 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.

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:books: Documentation preview :books:: https://sphinx-hoverxref--236.org.readthedocs.build/en/236/

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:books: Documentation preview :books:: https://read-the-docs-sphinx-hoverxref--236.com.readthedocs.build/en/236/

[onerandomusername]

Would you mind updating this to be based on version 1.2.0?

[humitos]

@shiftinv @onerandomusername I just released 1.3.0. Please, let me know if it works as you expected 💯

[shiftinv]

@humitos Awesome, much appreciated! Everything seems to be working fine, all references are now being found :tada: