fuzz: enable passing a max value to FuzzedDataProvider::ConsumeEnum() #21855

FuzzedDataProvider::ConsumeEnum(), last updated in e3d2ba7c70b13a2165020e45abf02373a1e953f7 remains unused in the codebase as it requires the presence of a |kMaxValue| in the enum aliased to the largest value to be fuzzed, e.g. enum class Foo { SomeValue, OtherValue, kMaxValue = OtherValue }. It seems unlikely that we'll change the enums in the codebase for this. To make ConsumeEnum useable for us, change it to allow passing the max_value to be fuzzed in the contiguous range of {0..max_value}.

Extracted from 6902abc804f3a96292050c63b9cad25ff628bef7 in #21843 which augments rather than replaces ConsumeEnum(), commit to be dropped there if merged here.

Concept ACK

Historically we've kept FuzzedDataProvider.h in sync with upstream (LLVM's FuzzedDataProvider.h) without any local modifications.

If we cannot upstream those changes then perhaps a helper can be added to the local src/test/fuzz/util.h? :)

@practicalswift That makes sense, thanks for the perspective. I'll look at doing that.

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Conflicts

Reviewers, this pull request conflicts with the following ones:

• #21843 (p2p, rpc: enable GetAddr, GetAddresses, and getnodeaddresses by network by jonatack)

If you consider this pull request important, please also help to review the conflicting pull requests. Ideally, start with the one that should be merged first.

Closing for now.