Use feedback as package and add format option

[zmoog]

Motivation

I want a human-friendly table based format for interactive use, and a robot-friendly JSON based format to compose richer workflows with other tools.

$ classeviva grades list --limit 2
+------------+-------+-----------------+-------------------------------+
| DATE       | GRADE | SUBJECT         | NOTES                         |
+------------+-------+-----------------+-------------------------------+
| 2022-05-02 | 7½    | COMPORTAMENTO   | comportamento della settimana |
| 2022-04-27 | 9     | ARTE E IMMAGINE |                               |
+------------+-------+-----------------+-------------------------------+%

Change description

Add a new feedback package copied inspired by the Arduino CLI. Commands can use feedback to send messages and errors to the user. In addition, a PrintResult() is available to print structured result as text, JSON and other potential formats in the future.

Commands can use the Result interface to implement rich formatting of their results.

Reviewer checklist

• PR address a single concern.
• PR title and description are appropriately filled.
• Changes will be merged in main.
• Changes are covered by tests.
• Logging is meaningful in case of troubleshooting.
• Docs are updated (at least the README.md, if needed).
• History is clean, commit messages are meaningful (see CONTRIBUTING.md) and are well-formatted.