TL;DR

Added support for fetching transactions by hash through the RPC client.

What changed?

• Added a new RawTransaction type alias in the common package
• Generalized the RPCFetchBatch function to RPCFetchSingleBatch to work with any key type, not just block numbers
• Added GetTransactionParams function to support transaction hash parameters
• Implemented GetTransactions method in the RPC client to fetch transactions by hash
• Added SerializeTransactions function to convert raw transaction data to the internal format
• Added Close method to the IRPCClient interface and updated the mock accordingly

How to test?

1. Fetch transactions using the new method:

client := rpc.NewClient(...)
transactions := client.GetTransactions([]string{"0x123...", "0x456..."})

2. Verify that transaction data is properly serialized and contains the expected fields
3. Test with both valid and invalid transaction hashes to ensure error handling works correctly

Why make this change?

This change enables direct fetching of transactions by hash, which is useful for scenarios where we need to retrieve specific transactions without fetching entire blocks. This improves efficiency when only transaction data is needed and the containing block is not relevant.