fix: add ethers types to contracts-node and contracts-frontend

[mrice32]

Motivation

Importing ethers event types from contracts-node doesn't work.

Summary

You can now import ethers event types by doing the following:

import { MyContractEthersTypes } from "@uma/contracts-node";

const myVar: MyContractEthersTypes.SomeEvent = ...

Testing

Check a box to describe how you tested these changes and list the steps for reviewers to test.

• [x] Ran end-to-end test, running the code as in production
• [ ] New unit tests created
• [ ] Existing tests adequate, no new tests required
• [ ] All existing tests pass
• [ ] Untested

Issue(s)

N/A