Use a logger with different logging levels

Currently, inside of the Guess.js webpack plugin there are a lot of statements in the form:

if (this._config.debug) {
  console.warn(...);
}

Instead of having this duplication of this._config.debug checks, it’d be better if we isolate the logic into a logger with different logging levels. We can either create a custom logger (no dependencies, smaller payload) or go with an existing one (code reuse).

[mgechev]

@vprasanth looks great! Just merged the PR which introduced the logger & the initial refactoring. Feel free to replace the other console occurrences 😃

[vprasanth]

Hey, sorry for the delay, was at a cottage this weekend 😃

Anyways, I ended up adding a couple more log levels – but set the logger to DEBUG. I added the additional levels to cover error and warn. So in total there is DEBUG, INFO, WARN, ERROR, and OFF. Default for the logger is set to INFO.

I’ve so far only updated the prefetch-aot-plugin file, I noticed some other places within the guess-webpack package that use console, wasn’t sure if you wanted those updated as well. Figured I’d wait for a review then update the rest if wanted. Let me know 😃