Extend ASYNC110 to also warn if looping a `checkpoint()`

[jakkdl]

There being two sleep-related confusions can plausibly cause a bit of confusion, this code will raise TRIO115 (replace sleep(0) with checkpoint) and TRIO110 (replace looped sleep with an Event)

while foo():
  await trio.sleep(0)

but if the user resolves the ASYNC115, then ASYNC110 will also stop warning. I don't think it's something super common, but it happened in python-trio/trio#2947 (review) - so plausibly might happen again.

[Zac-HD]

Yeah, makes sense - while ...: checkpoint() is pretty inefficient so hopefully it's also rare, but that's even more reason to add it to the rule 👍