Support for address labels

One of the core functionalities of this project is to provide decoded information for given UserOp and Errors and it'll be easy to understand the results of decoded UserOp and Errors, if addresses also gets a label.

There should be a service that accepts an address and networkId and returns a label string which can be used to add to decoded information of UserOp or Errors to make it more human readable.

Addresses which needs labels are smart account factories, paymasters, token addresses or any other smart contract which is involved in UserOp execution.

This service should be easily extensible in terms of adding more labels.

The issue names no files, tests, or entry points; start by locating the existing UserOp and Error decoding flow. Trace where decoded information is assembled, then define the address-and-network label service around that flow. Done means relevant smart-contract addresses can receive labels that appear in decoded results, with the label source extensible for future additions.

Written by the indexing model from the issue text.