* add a plain text email template
* use plain text email template for file based emails
* add config option to SMTP emails named disable_html_emails
* config option is a boolean that when set to true will only send plain text emails
* add docs for more complex SMTP notifier options
* update template
* add rfc1341 multipart logic to notifier
* check for errors after identity_verification
* * fix nil ptr
* go mod tidy
* remove needless checks
* * use multipart/atlernative instead
* * add rfc5322 compliant date header
* * fix linting issues
- Adjust AUTH LOGIN functionality to be closer to AUTH PLAIN
- Removed: secure (notifier smtp conf) boolean string
- Added: disable_verify_cert (notifier smtp conf) boolean
- disables X509 validation of certificates
- Added: disable_require_tls (notifier smtp conf) boolean
- allows emails to be sent over plain text (for non-authenticated only)
- Added: trusted_cert (notifier smtp conf) string (path)
- allows specifying the path of a PEM format cert to add to trusted cert pool
- Make SMTP notifier return errors on connection over plain text
- Make SMTP notifier return errors on TLS connection with invalid certs
- Implemented various debug logging for the SMTP notifier
- Implemented explicit SMTP closes on errors (previously left con open)
- Split SMTPNotifier Send func to seperate funcs for:
- writing future test suites and startup checks more easily
- organization and readability
- Add details of changes to docs/security.yml
- Adjust config.yml's (template and test) for the changes
