[lib][native][web][keyserver][landing] Update to Ethers.js 6

Summary:
We use Ethers.js for resolving ENS addresses across much of our stack.

As part of addressing the deprecation of the Ethereum testnet Goerli, we need to update to Ethers.js. See point 1a here.

Test Plan: Unit tests will be fixed later in the stack. I also tested that ENS resolution still worked in native, web, and keyserver

Reviewers: atul, ginsu

Reviewed By: ginsu

Subscribers: tomek

Differential Revision: https://phab.comm.dev/D11485