Exponential back-off for process restarting

[gustavohenke]

Title.

$ conc --restart-tries 4 --restart-after exponential "date && exit 1"
[0] Fri 12 Jan 2024 14:10:56 -03
[0] date && exit 1 exited with code 1
[0] date && exit 1 restarted
[0] Fri 12 Jan 2024 14:10:57 -03
[0] date && exit 1 exited with code 1
[0] date && exit 1 restarted
[0] Fri 12 Jan 2024 14:10:59 -03
[0] date && exit 1 exited with code 1
[0] date && exit 1 restarted
[0] Fri 12 Jan 2024 14:11:03 -03
[0] date && exit 1 exited with code 1
[0] date && exit 1 restarted
[0] Fri 12 Jan 2024 14:11:11 -03
[0] date && exit 1 exited with code 1

Closes #265

[coveralls]

coverage: 99.322% (+0.006%) from 99.316%
when pulling 597a1f8 on exponential-backoff
into aedebc1 on main.

[gustavohenke]

Evidence https://github.com/ReactiveX/rxjs/blob/7.8.1/src/internal/testing/TestScheduler.ts#L18

[mscottnelson]

Very nice! Looks great! Thank you for adding this feature