feat:: configurable formatter

[fwal]

Hi! 👋

This is a proposal on how to enable customisation of the formatting step by adding the ability to add additional formatters programatically. In the example included in the test, a function type is formatted as a custom object defined by the consumer.

Example:

createFormatter(configuration, (formatter) => {
    formatter.addTypeFormatter(new MyFunctionTypeFormatter())
})

I'm looking forward to your feedback!

[domoritz]

This is awesome. Just one comment about naming.

Can you also add documentation and maybe an example to the readme?

[fwal]

I've added an example but having a bit of struggle with the naming of the configuration function (naming is one of the hardest parts with programming after all 😄) so I'll have to get back to you on that.

[domoritz]

Thank you for the docs. Yes, naming is hard. Maybe augment or augmentor?

[fwal]

Yeah that works, changed to FormatterAugmentor.