[Feature] Add Custom Formatter System

Right now there is just one way to format everything and it does not make everybody happy. Also it makes it hard for us to change it without potentially breaking things. So I propose the following:

• add a context setting to override a formatter class
• that formatter has attributes and methods to customize how things are emitted
• we have two classes for this: a default formatter that we keep improving and a legacy formatter that is as it looked like in click 5 which is super stable if you need a stable target

Things this would be used for:

• usage rendering
• wrapping of text
• colorization flags
• maximum width / minimum width of help output
• indentation style of help
• default value rendering etc.
• error messages