WEB3-276: feat: Add Account query functionality to Steel

[Wollac]

This PR adds the Account struct to enable querying Ethereum account information in both host and guest environments, similar to how Contract works for contract interactions.

Changes

• Add Account struct with host/guest implementations for querying account info
• Add documentation and examples showing usage patterns
• Add integration test demonstrating account queries including bytecode fetching

Usage Example

// Host environment:
let mut env = EthEvmEnv::builder().rpc(url).build().await?;
let account = Account::preflight(address, &mut env);
let info = account.bytecode(true).info().await?;

// Guest environment:
let env = evm_input.into_env();
let account = Account::new(address, &env);
let info = account.bytecode(true).info();

Testing

Added integration test account_info that:

• Verifies account information matches between preflight and execution
• Validates balance, nonce, code, and code hash against provider data
• Tests bytecode fetching functionality

Implementation Notes

• Follows same pattern as Contract with separate host/guest implementations
• Uses builder pattern for configuration (e.g., bytecode())
• Provides both error-handling (try_info()) and panicking (info()) variants

The implementation aims to provide a consistent interface alongside the existing Contract functionality while maintaining the same security and verification guarantees.

Fixes #380, WEB3-276

[linear]

WEB3-276 [Feature] Ability to prove historical account state (e.g. balance, nonce, codeHash, storageRoot) using Steel

[Wollac]

A Steel account query returns the corresponding revm::primitives::AccountInfo. This is a bit closer to the actual (revm) EVM execution, but it does not return the storage root (which is also inaccessible from inside the EVM) and the code is returned as revm::primitives::Bytecode instead of just Bytes. Alternatively, it may be preferable to define and return our own new type:

pub struct AccountInfo {
    pub nonce: u64,
    pub balance: U256,
    pub storage_root: B256,
    pub code_hash: B256,
    pub code: Option<Byte>,
}

[Wollac]

OK, I did a little research on this: The problem is the storage_root. Unfortunately, this is not accessible in EVM, so there is no easy way to get it from RPC or the revm DB. The only way is to call an eth_getProof just to get this value. This is possible, but would require a bit more code.
So do we think the storage_root is necessary? Otherwise the existing alternative would be sufficient and easier.

[nategraf]

Let's move on without the storage root then. If there becomes a use case for this, we can revisit, possibly adding a helper function of some sort to specifically get the storage root.

[nategraf]

Lovely!