* [MISC] Refactor and address most errcheck linter ignores
This is mostly a quality of life change.
When we first implemented the errcheck linter we ignored a number of items in our legacy codebase with intent to revisit down the track.
* Handle errors for regulation marks and remove unnecessary logging
* [MISC] Ignore errcheck recommendations for legacy code
Some of this is likely intended to stay how it is, some could use refactoring, for now we will mark is and ignore it from the linter to be potentially addressed in the future.
* [MISC] Ensure files are gofmt-ed
* [FEATURE] Customizable Email Subject
* allow users to optionally change email subject
* this is so they can more easily communicate the source of the email
* Update docs/configuration/notifier/smtp.md
Co-Authored-By: Amir Zarrinkafsh <nightah@me.com>
Co-authored-by: Clément Michaud <clement.michaud34@gmail.com>
Co-authored-by: Amir Zarrinkafsh <nightah@me.com>
