Update templates/10-mail.conf.j2 to explicitly define standard mailboxes (Drafts, Junk, Trash, Sent) within the inbox namespace.
This change ensures that:
- These folders are automatically subscribed (`auto = subscribe`).
- They are correctly flagged with `special_use` attributes, improving compatibility with IMAP clients.
- "Sent Messages" is also recognized as a Sent folder for broader client support.
Introduces functionality to install and configure Dovecot alongside Postfix to provide IMAP/POP3 services.
Changes include:
- Added tasks to install Dovecot packages (core, imapd, pop3d, lmtpd).
- Added templates for main configuration and conf.d files (auth, master, ssl, mail).
- Defined default variables for protocols, SSL settings, and Maildir location.
- Enabled Postfix SASL and LMTP integration options.
- Added a handler to restart the Dovecot service.
- Updated README.md with the new configuration variables and usage instructions.
