eslint deprecated rules

[readeral]

ESLint deprecated the following rules used in this config in favour of @stylistic/eslint-plugin:
no-floating-decimal
wrap-iife
no-confusing-arrow

Stylistic recommend using stylistic.configs['disable-legacy'] to enable smooth migration where packages (like this one) still include the deprecated rules. See migration guide here https://eslint.style/guide/migration#disable-legacy-rules

The Stylistic rule factory (essentially their defaults) includes no-floating-decimal and wrap-iife, but disabling legacy rules requires setting up no-confusing-arrow manually to match eslint-config-lwc

It would be good to either have docs that give guidance for using stylistic while keeping feature parity with eslint-config-lwc, or to move to incorporate stylistic into this config set.

I'm happy to make a PR for updating docs if there's interest in merging the change, I assume shifting to @stylistic/eslint-plugin will require more careful architectural work for eslint-plugin-lwc and whatever ramifications it may have conflicting with prettier in that package (I've personally dropped prettier for all my LWC JS in favour of stylistic, but that's very subjective!)