feat: add option to interrupt test runner

[grandizzy]

At this moment there's no way to programmatically stop a test run in process with replay, which simply loops until a failure or all configured cases pass

proptest/proptest/src/test_runner/runner.rs

Line 609 in 24412f5

while self.successes < self.config.cases {

It would be nice to be able to interrupt this loop at will so in a setup with multiple tests started at the same time (not using fork feature but rather parallelized using rayon for example) following scenarios could be achieved:

• fail fast: when one of these test fails then the other tests are interrupted
• timeout (not using rusty fork / fork timeout feature): interrupt all running tests when timer (started outside tests) expires

[grandizzy]

made a PR with proposed implementation #461 @matthew-russo please have a look when time permits. thank you!

[grandizzy]

@matthew-russo any thoughts re this issue and associated PR really appreciated, thank you!

[grandizzy]

ping @matthew-russo any insight re this issue and PR #461. thank you!