extract semaphore logic out of WeightBoundedQueue to allow for sharing the weigher

[m-trieu]

Factor out semaphore logic out of WeightBoundedQueue to allow for sharing the weigher

R: @scwhittle

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[github-actions]

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[m-trieu]

@scwhittle ready to for review, the failure to unrelated thanks!

[m-trieu]

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