HIR visitor that short-circuits on the first ETH-sending expression and queues statically
resolved callees for transitive exploration by the outer worklist loop.
True if expr unambiguously moves ETH out of the contract: a non-zero {value: x} call
option, .transfer/.send with a non-zero amount, low-level .delegatecall/.callcode
(drainable via selfdestruct), or the selfdestruct builtin. Only literal 0 is treated as
a zero amount, and sends targeting this contract’s own address are not exits.