This introduces functionality to manage local Dovecot users utilizing a
static `vmail` system user and a flat password file.
Key changes:
- Added `dovecot_users` configuration list to defaults.
- Implemented creation of `vmail` user and group (uid/gid 5000).
- Added logic to generate a random security token using `pwgen` to prefix
user passwords.
- Created `auth-dovecot-users.conf.ext` and `dovecot-users.j2` templates
to handle `passwd-file` authentication.
- Updated `10-auth.conf` to include the new local users configuration.
- Updated README with usage instructions and token details.
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.
