Extend the shared MetaMask ESLint config

[rekmarks]

Mobile should extend:

• @metamask/eslint-config, for all files
• @metamask/eslint-config-jest, for tests

As discussed, rules can be disabled in the local ESLint config to make the overhead of migrating smaller.

For related work, see: MetaMask/eslint-config#170, MetaMask/eslint-config#171

This is a major change for dev experience (has no impact on users). After this change takes place, the engineers will have to code in a different way (before / after moment)

[rekmarks]

When mobile does this, it's also a significant opportunity to get on the same Prettier config (although that change would make sense to do in a separate PR). If the mobile team feels strongly about its Prettier config, we should discuss what can be done to reconcile our differences of opinion.

Personally, I find 120 print width far too much.

[andrepimenta]

I believe this is an important step to share more code and configurations with both products.

Context: https://consensys.slack.com/archives/G1L7H42BT/p1618866302118900

Started looking into this here: https://github.com/MetaMask/metamask-mobile/compare/improvement/shared-metamask-eslint-config

[mobularay]

High impact for Engineers - need to align on timing as it changes the way code works. Engineers to discuss before working on this workl.