feat(dependencies): Remove direct debug dependency

[daffl]

This pull request removes the direct dependency on the debug module for the following reasons:

• Makes it easier support for other platforms (like Deno, see Deno Support? #1964)
• Reduces the client side core production bundle size by at least 20%
• Lets you pipe Feathers debug information into your own logger

Normal debug support can easily be added like this:

const feathers = require('@feathersjs/feathers');
const debug = require('debug');

feathers.setDebug(debug);

This change will apply to all @feathersjs/module.

To use your own logger:

const feathers = require('@feathersjs/feathers');
const winston = require('winston');

feathers.setDebug(name => (...args) => winston.debug(name, ...args));