Rename flip by bernoulli

[ngeiswei]

I suggest to rename flip in the standard library by bernoulli.

I understand that flip is the name used in Church, however in Haskell flip is a combinator, see https://hackage.haskell.org/package/base-4.20.0.1/docs/Prelude.html#v:flip. Thus Haskell uses bernoulli, see https://hackage.haskell.org/package/mwc-random-0.15.1.0/docs/System-Random-MWC-Distributions.html#v:bernoulli, which I think is a great name for the job.

[ngeiswei]

Also, I think that function would be more useful if it takes a bias as parameter, as in Church and Haskell.

[Necr0x0Der]

This function was introduced mostly for testing automatic conversion of grounded atoms between Rust and Python. Apparently, we need to have a separate library for random functions, and I'd say that this library should provide not just random functions, but samplers supporting different sampling strategies. Thus, this implementation is temporary in any case. You can go ahead and rename it if you prefer, but please check if there are still tests with its use