[ty] Fix binary intersection comparison inference logic (#18266)
## Summary
Resolves https://github.com/astral-sh/ty/issues/485.
`infer_binary_intersection_type_comparison()` now checks for all
positive members before concluding that an operation is unsupported for
a given intersection type.
## Test Plan
Markdown tests.
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Co-authored-by: David Peter <mail@david-peter.de>
