Transform into a complete CLI Mail App

### Implement various other features of a typical mail app in the CLI

- User should be able to see a list of all labels and navigate to mails contained in them.
- On selecting a particular mail he should be able to see the content of the mail.
- Allow user to delete and trash some specific message
- Allow user to add/delete a mail to draft and retrieve all emails from the draft

Refer the [doc](https://developers.google.com/gmail/api/reference/rest)

Start by reading the repository's existing CLI entry points and the linked Gmail API documentation; the issue does not name specific files or tests. Map the current mail flow before planning the label, message-viewing, trash/delete, and draft workflows. Done means each listed workflow is available from the CLI and works with Gmail.

Written by the indexing model from the issue text.