feat: Add Unit Tests for get_batch_pubdata endpoint

[toni-calvin]

Description:

Overview:

• This pull request aims to enhance the test coverage for the get_batch_pubdata endpoint within the EthSender module. The primary objective is to validate the correctness of the endpoint by comparing the expected pubdata with the actual result obtained through the API call.

Changes Made:

• Introduces unit tests for the get_batch_pubdata endpoint.
• Utilizes the TestHelper struct within the EthSender module to facilitate the creation of batches, addition of pubdata, insertion, and commitment of batches.
• The testing process involves invoking the endpoint for a specific batch number and comparing the obtained result with the expected pubdata inserted during batch creation.
• For the current phase, the PR includes logging statements to display the inserted and committed L1 batch, as well as the result obtained from the endpoint.

For running the test: zk test rust -- get_batch_pubdata_impl --nocapture

[jordibonet-lambdaclass]

I think you accidentally left out the character ` before None.

[jordibonet-lambdaclass]

Could we consider using iter().all() to compare if all elements of partial_pubdata are zeroes?
This approach can potentially optimize performance by avoiding unnecessary allocation of a new vector of zeroes, particularly beneficial for larger vectors. The suggested change would look like:

if partial_pubdata.iter().all(|&x| x == 0) {
    Bytes::default()
} else {
    partial_pubdata.into()
}

Your thoughts on this optimization would be appreciated. Thank you!