Proposal: Providing a no-runtime-rng version using a feature gate

[sjfhsjfh]

Currently, ahash and getrandom is used

ahash: default-features = false, features = ["std"] getrandom: rewrite a small rng using rand = { version = "0.9.0", default-features = false, features = ["small_rng"] }

These optional modifications can be applied when the runtime-rng feature flag is not present.

I made a working example here, but I'm not very sure if this is the best way of doing this and there're some problems(e.g. the image feature uses rand crate, this can be seen from cargo tree --target all -i getrandom), so it is currently just a proposal.