[Feature] Support truncated key for JsonStorageKey

[mattsse]

Component

rpc, serde

Describe the feature you would like

alloy/crates/serde/src/storage.rs

Line 31 in b2278c4

pub struct JsonStorageKey(pub B256);

ref https://github.com/ethereum/go-ethereum/blob/a5fe7353cff959d6fcfcdd9593de19056edb9bdb/internal/ethapi/api.go#L741-L744

this exists for backwards compatiblity, which I think we don't need to focus on but if the input is a 32bytes hex string then this should be preserved in the serde roundtrip

this can be solved with a helper enum that is similar to:

alloy/crates/eips/src/eip1898.rs

Lines 665 to 674 in b2278c4

	/// Either a hash _or_ a block number
	#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
	#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
	#[cfg_attr(any(test, feature = "arbitrary"), derive(arbitrary::Arbitrary))]
	pub enum HashOrNumber {
	/// The hash
	Hash(B256),
	/// The number
	Number(u64),
	}

but with B256,U256, B256 must be decoded first

TODO

• introduce helper enum
• replace wrapped value of JsonStorageKey

Additional context

No response