used-before-assignment false positive for named expressions in a not-first position in container

[jacobtylerwalls]

This raises used-before-assignment:

def expression_in_ternary_operator_inside_container_later_position():
    """Named expression follows unrelated item in container"""
    return [23, val3 if (val3 := 'something') else 'anything']

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The check for BaseContainer should also check all elements. I can handle that in another PR.

Originally posted by @jacobtylerwalls in #8176 (review)