Tiny punctuation change

Tiny punctuation change

optionally re-add the "write on async/await path" code rather than relying on the backlog; add supporting code for both; heartbeat should also help clear down anything in the backlog

seeing a lot of "MuxerIsCollected" failures on CI; it genuinely *is* collected in all local scenarios, so I'm suspicious that this is timing/load related; try to make it less twitchy

fix #1079 - make `RedisValue.Unbox` far more forgiving on inputs; also, make `RedisValue.Box` try to be more frugal (return boxed primitives rather than boxed RedisValue when possible; support reused objects for common values)