libafl_bolts: rands super mega ultra giga house cleaning of doom

[flyingmutant]

Fixes #2101.

[domenukk]

Do we really want to remove working rngs?

[flyingmutant]

I've written the rationale in the commit message. This is a controversial thing, for sure, I can leave them in if you prefer. My idea was to leave only some kind of "Pareto frontier" of generators, with romuduojr being the fastest, xoshiro being the one of the most popular, and sfc being the all-around solid choice.

[addisoncrump]

Instead of removing RNGs, please mark them with #[deprecated = "<reason>"]. You can use #[allow(deprecated)] in tests and implementations.

Part of the reason for LibAFL's existence is not just to have good perf all the time, but to have the best performance for the given task. Suppose someone comes along and wants to evaluate the actual effects of low entropy random in fuzzing; it is totally legitimate for them to select "bad" RNGs. This is a bit of a contrived example, of course, but this is also relevant for e.g. reproduction works and avoiding breaking user code where possible/reasonable.

[flyingmutant]

All PRNGs are back in! I decided not to deprecate anything in this PR -- this can be done separately.

[domenukk]

Thank you! :)

[addisoncrump]

@flyingmutant Can you add an issue to deprecate these RNGs? Don't want to forget to do so.