[red-knot] fix unions of literals, again (#17534)
## Summary
#17451 was incomplete. `AlwaysFalsy` and `AlwaysTruthy` are not the only
two types that are super-types of some literals (of a given kind) and
not others. That set also includes intersections containing
`AlwaysTruthy` or `AlwaysFalsy`, and intersections containing literal
types of the same kind. Cover these cases as well.
Fixes #17478.
## Test Plan
Added mdtests.
`QUICKCHECK_TESTS=1000000 cargo test -p red_knot_python_semantic --
--ignored types::property_tests::stable` failed on both
`all_fully_static_type_pairs_are_subtypes_of_their_union` and
`all_type_pairs_are_assignable_to_their_union` prior to this PR, passes
after it.
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Co-authored-by: Alex Waygood <Alex.Waygood@Gmail.com>
