Event aliasing for contract bindings

[WilfredTA]

Motivation

Smart contracts written in Solidity can include methods and events with the same name, so long as their signatures are different.

The contract crate provides utilities for generating bindings to a contract's ABI. Because Rust does not support function overloading, these utilities enable the user to add method_aliases, which changes the function's name in the generated contract bindings.

The crate did not provide aliasing capabilities for event definitions.

Solution

The associated function add_event_alias was added to the Abigen struct within ethers-contract::ethers-contract-abigen.

PR Checklist

• Added Tests
• Added Documentation
• Updated the changelog

[WilfredTA]

Note: Linter check fails because rustfmt adds a trailing comma to one of the tests which causes the test to fail.

[mattsse]

Some suggestions and nits.
Tes cases look good!

Also since the self.event_aliases.get is used quite often, consider creating a function for it, fn get_event_alias or something

[mattsse]

lgtm