Retry `assume` and `.filter` inside of `#[rule]`

[Liam-DeVoe]

We decided not to include #[precondition] in state machines for now, breaking from Hypothesis's design. One consequence of this is we can't filter out invalid rules ahead of time, and any failed assume or .filter inside of stateful rules rejects the entire test case.

The Hegel state machine should wrap each rule and retry failed assumptions up to some limit, rather than aborting the entire test case.

[DRMacIver]

It already does this! We catch the failed assumption and move on to the next rule.