feat: Added integration with the built-in logging package

[dylan-robins]

This PR integrates the built-in logging package, as listed in the Cleo 3.0 writeup (#415 ). Implementation is of course subject to change, but I thought I'd get the ball rolling :)

Here's what I did:

• Added an OutputHandler class, allowing logging to emit LogRecords to a cleo.io.outputs.output.Output
• Added a method to cleo.application.Application which attaches an OutputHandler to the root logger, and configures it to have a log level that is coherent with Cleo's one.
• Added unit tests ensuring all this works as expected.

Here are some open points that I know we need to discuss:

• How should we map logging's log levels to Cleo's verbosity levels? Current implementation is as follows:
  • Quiet: CRITICAL (but nothing gets printed anyway so whatever)
  • Normal: WARNING
  • Verbose: INFO
  • Very verbose: DEBUG
  • Debug: DEBUG
• Formatting:
  • Should the stuff coming from the logging handler have some sort of prefix or something to distinguish them from what is coming directly from output.write_line()?
  • The formatter styles for error, warning, info and debug need to be defined.