[typing] Fix minor typing of pip._internal sub packages utils, exceptions, locations, self_outdated_check

[pelson]

Follows on from issues identified through #13599.

As before, intentionally targeting zero functional change.

[pelson]

This one is really about type narrowing, since mypy doesn't do that for type(self) is not type(other). The reason for the change at all comes down to the fact that self.secret == other.secret isn't recognised as a bool when other is Any.

[pelson]

Reflecting on this, I probably would rewrite this for clarity as:

    def __eq__(self, other: object) -> bool:
        if type(self) is type(other):
            # The string being used for redaction doesn't also have to match,
            # just the raw, original string.
            return self.secret == cast(HiddenText, other).secret
        return False

[sepehr-rs]

Hi @pelson, thanks again for your contribution to pip!
This PR appears to be mostly internal again, so I’ve added the 'skip news' label.
Since these typing improvements seem related, it might be worth considering grouping similar changes into a single PR in the future, which can sometimes make reviews a bit easier for maintainers.
In any case, thanks for working on improving the typing coverage here!