Allow `Unstructured` to be backed by an iterator of bytes instead of a byte slice?

In our use case, we are not using Arbitrary for fuzzing, but simply for creating arbitrary fixture values in tests. Currently we create a 10MB static Vec<u8> of random noise and use that as our Unstructured data. However this is annoying since it requires 10MB of memory overhead, and sometimes even then we run out of bytes.

I am wondering if it would be valid to have two flavors of Unstructured, one backed by a byte slice, presumably for fuzzing, and one backed by an infinite iterator of bytes which can never be exhausted. I experimented with a PR for doing this and got some basic tests passing, but don't know how valid it is in the grand scheme. I did find that some functionality is indeed dependent on the fixed byte slice, so at the very least some extra UX effort would have to be made to provide slightly different interfaces for different Unstructured flavors.

I understand if this wouldn't be worth the effort but I guess I am primarily wondering from a motivational standpoint why Unstructured is backed by a byte array instead of an iterator, and only secondarily asking for some feedback on the feasibility of using infinite iterators. Note: I know next to nothing about fuzzing.

Start with the Unstructured entry point and review the referenced PR experiment, focusing on which functionality depends on a fixed byte slice. Check the existing basic tests and determine whether an iterator-backed variant can preserve the current interfaces. Done means a maintainer-approved design and tests that establish the supported behavior and its limits.