feat(l2): add helper functions for l2 eth client

[tomip01]

Motivation

We want this new functions that will be useful for rex and future use.

Description

Add get_batch_number() function to call ethrex_batchNumber
Add send_ethrex_transaction() function to call ethrex_sendTransaction

[Copilot]

Pull request overview

This PR adds a helper function get_batch_number() to retrieve the current batch number from the L2 RPC endpoint ethrex_batchNumber, which will be useful for rex and future components.

• Adds get_batch_number() function to query the ethrex_batchNumber RPC endpoint
• Introduces GetBatchNumberError enum with variants for JSON serialization, RPC errors, and integer parsing
• Integrates the new error type into the main EthClientError enum

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
crates/networking/rpc/clients/eth/errors.rs	Adds GetBatchNumberError enum with SerdeJSONError, RPCError, and ParseIntError variants, and integrates it into EthClientError
crates/l2/networking/rpc/clients.rs	Implements get_batch_number() function that calls ethrex_batchNumber RPC endpoint and parses the hex-encoded batch number response

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[github-actions]

Lines of code report

Total lines added: 82
Total lines removed: 0
Total lines changed: 82

Detailed view

+----------------------------------------------------+-------+------+
| File                                               | Lines | Diff |
+----------------------------------------------------+-------+------+
| ethrex/crates/common/types/transaction.rs          | 3207  | +2   |
+----------------------------------------------------+-------+------+
| ethrex/crates/l2/networking/rpc/clients.rs         | 185   | +58  |
+----------------------------------------------------+-------+------+
| ethrex/crates/networking/rpc/clients/eth/errors.rs | 369   | +22  |
+----------------------------------------------------+-------+------+

[JereSalo]

I see the enum above this has a TODO that says Move to L2, do you know if there's an issue created for that? Would it be easy to achieve?

[tomip01]

I didn't find any. The closes was this

[JereSalo]

Looks good, idk if it was tested but it would be good if it was

[tomip01]

Looks good, idk if it was tested but it would be good if it was

It tested it manually