[Console] Added the ability to return the default answer in a question

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | yes
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | none
| License       | MIT
| Doc PR        | symfony/symfony-docs#4254

This gives the option of showing the default answer along with the question. The documentation is a work in progress.
Thinking about usability, should the default be shown by default?