UI component model

[jvalkeal]

We want to make it easy to create higher "UI" level components user to interact providing ways to ask various types of inputs like texts and selectors. Essentially what you see in https://github.com/cli/cli and https://github.com/SBoudrias/Inquirer.js.

Value for this is that user don't need to know all low level details about working with console as things get quite complex when working with inputs, ansi escape characters(ie moving cursor) and unicode charaters(something more sophisticated than plain text).

[jvalkeal]

Closing this now as we have basic things under https://github.com/spring-projects/spring-shell/tree/main/spring-shell-core/src/main/java/org/springframework/shell/component.

Docs coming in a separate issue as well as further tweaks.