Support flag for disabling prettier when running eslint CLI

[spalger]

When running ESLint from the command line it takes a whole lot of time to run. There are two things I think we could do to improve things:

1. Help disabling prettier by adding support for --no-prettier which would be converted to --rules {"prettier/prettier": "off} in the ESLint wrapper

2. Parallelize eslint execution. eslint-parallel is a simple project to do this, and esprint is a similar project, which runs a server in the background to maintain results and make eslint across the whole project nearly instant.

Tackling option 1 seems pretty simple, but devs would have to opt into disabling prettier and would get only a subset of the results they would get from CI, so I'm not in love with this idea.

Option 2 seems like a more correct solution, just need to evaluate some of the options.

[elasticmachine]

Pinging @elastic/kibana-operations (Team:Operations)