hardhat_api: Implement hardhat_impersonateAccount API endpoint

[MexicanAce]

Description:

The hardhat_impersonateAccount endpoint needs to be implemented. The purpose of this endpoint is to impersonate an account given the address. Hardhat docs for reference.

// Interface in the `trait`
#[rpc(name = "hardhat_impersonateAccount")]
fn impersonate_account(
    &self,
    address: Address,
) -> BoxFuture<Result<bool>>;

// Actual code in the `impl`
fn impersonate_account(
    &self,
    address: Address,
) -> BoxFuture<Result<bool>> {
    // TODO: Solution here
}

Expected response

Command returns proper response:

curl -X POST http://localhost:8011 \
     -H "Content-Type: application/json" \
     --data '{
       "jsonrpc": "2.0",
       "id": 1,
       "method": "hardhat_impersonateAccount",
       "params": ["0x36615Cf349d7F6344891B1e7CA7C72883F5dc049"]
     }'

Response:

{"jsonrpc":"2.0", "result":true, "id":1}

Requirements:

1. Implement the API:

   • The endpoint should return true if successful in impersonating the given address, otherwise false.
   • Anytime a request is made to eth_sendRawTransaction, it is intercepted and we check if the user is supposed to be impersonated. If it is, then we impersonate and bypass verification for transaction execution.
   • Ensure the method executes the call reliably and efficiently.
   • Ensure errors are properly returned.

2. Unit Tests:

   • Write unit tests to verify the functionality of the impersonate_account method.
   • Ensure coverage for multiple edge-case scenarios.

3. Documentation:

   • Add inline Rust documentation (/// comments) detailing the method's purpose, return values, and any potential edge cases or error scenarios.
   • Update SUPPORTED_APIS.md with updated documentation and examples.
   • (Optional) Add request to test_endpoints.http for easier manual verification.

Task Checklist:

• Implement the impersonate_account method.
• Write unit tests for the impersonate_account method.
• Add inline documentation for the hardhat_impersonateAccount endpoint.
• Update documentation for the hardhat_impersonateAccount endpoint in SUPPORTED_APIS.md.

Additional Notes:

If you're an external contributor looking to take on this issue, please comment below to let us know you're working on it. If you need further clarification on the requirements or need assistance with anything related to the implementation, feel free to ask!

[MexicanAce]

Note: This Issue will require some extra investigation, as this is a best guess effort.

Also, since eth_sendTransaction is no longer supported in zkSync Era, I don't think we'll be able to natively match the underlying functionality of any hardhat helpers for account impersonation (since we use eth_sendRawTransaction)

[MexicanAce]

Implemented with #125