FutureJob and SequentialJob handle random seeds differently

[jeremyrcoyle]

SequentialJob and FutureJob don't handle seeds the same. See an sl3 example here: tlverse/sl3#402

It seems we should make SequentialJob act more like FutureJob:

The help on future says:

To use a fixed random seed, specify a L'Ecuyer-CMRG seed (seven integer) or a regular RNG seed (a single integer). If the latter, then a L'Ecuyer-CMRG seed will be automatically created based on the given seed.

And it's implemented here: https://github.com/HenrikBengtsson/future/blob/c764c05fc72a0e0b036cf19ada4563f35b66b82f/R/rng_utils.R#L130-L142

So if we similarly dictate the kind of seed here: https://github.com/tlverse/delayed/blob/master/R/Job.R#L98, we should hopefully replicate the behavior

[jeremyrcoyle]

fixed in #27 for sequential futures. Probably not possible to fix for parallel futures