signer/core: fix incorrect EIP-712 recursive encoding of nested bytes arrays

[crStiv]

This PR fixes issue #30979 where nested bytes arrays (bytes[]) were incorrectly encoded recursively. The fix adds special handling for bytes arrays in the encodeArrayValue function to treat them as primitive types rather than nested arrays.

Changes:

• Added special case for bytes arrays in encodeArrayValue
• Added test case to verify the fix
• Updated documentation

The issue was causing encoding errors when dealing with nested bytes arrays, as each byte in the array was being treated as a separate array element rather than as part of a single bytes value.

closes #30979

[holiman]

Thanks for looking into this. Howevder, the test you added fails,

=== RUN   TestEncodeNestedBytesArray
    types_test.go:258: Failed to hash struct with nested bytes array: domain is undefined

Also, a lot of other tests fail (https://ci.appveyor.com/project/ethereum/go-ethereum/builds/51265439/job/01cck5hat24897m0#L1126) , and the imports need to be sorted (https://ci.appveyor.com/project/ethereum/go-ethereum/builds/51265439/job/cxswaevl9mqlc8v7#L56)

[crStiv]

@holiman made a change, did I understand correctly what you wanted to be changed?

[holiman]

did I understand correctly what you wanted to be changed?

I am not sure. I really just (so far) commented on failing tests. We never ever check in a failing test

[holiman]

The test that you added, and several others, are still failing: https://ci.appveyor.com/project/ethereum/go-ethereum/builds/51280768/job/sa6l473v1d5lp1vl#L1125 .

I don't understand. Do you run the test locally? Because I don't see how it could possibly succeed?