add standard and prepare for standard lint

[Uzlopak]

This PR is also for discussing if we should switch to standardjs, like fastify core.

This PR adds all the changes, which need to be done manually to be conform with standardjs. It is easier to review the changes, which have to be done manually before doing a lint:fix, than doing a lint:fix and then fixing manually the stuff, which standardjs could not handle.

I excluded deps/encoding as it is kind of a standalone part and messing with it is potentially critical. Also encoding-indexes.js is a huge file, so having it in a "compressed" format makes sense.

So if we agree on using standardjs like fastify core does, we should merge this, and in a second PR we would just run npm run lint:fix and changing to standard for npm run lint in package.json.Also dont forget to add standard to extends attribute of eslint-configuration.

Checklist

• run npm run test and npm run benchmark
• tests and/or benchmarks are included
• documentation is changed or added
• commit message and code follows the Developer's Certification of Origin
  and the Code of conduct

[Uzlopak]

Maybe we have to downgrade to eslint 7, till standard/eslint-config-standard#193 lands

[Uzlopak]

But we could also independently integrate the code changes to be prepared anyway.

[Uzlopak]

@kibertoad I downgraded eslint for now. Just want to make sure: Still holding on to your approval?

[Uzlopak]

Preparing now the follow up, to enforce standard js

[kibertoad]

sure, I'm ok with that