Allow usage of ESLint v7

[forcedotcom]

Allow usage of ESLint v7

[pozil]

Dropping these changes as I've been told that his library is not officially supported and that we should use the force:lightning:lint CLI command.

[touzoku]

@pozil actually it is now officially supported, but I am not entirely sure 😓 @trevor-bliss what'd you say?

[pozil]

Yes, you're right @touzoku. There was an internal debate and the outcome was:

• this plugin is officially supported but it needs to evolve to integrate additional rules from other linting projects including the ones used by the CLI command.
• the force:lightning:lint CLI command will be deprecated.

I'll reopen the issue.

[trevor-bliss]

Well I wouldn't call it "officially supported" until the package is updated and someone internally who works on Aura reviews the rules, but the plan @pozil outlined above is correct for the future.