* Enable 'secure' option for pwgen
As per the [pwgen manual](https://linux.die.net/man/1/pwgen, "pwgen manual"), the "-s"(secure) option instructs pwgen to generate completely random passwords, where as the default for pwgen is to generate more memorable passwords. Since, the passwords generated in this part of the installation process are to be "remembered" by the dot env file, I believe that users may benefit from the additional entropy provided by the "-s" option in pwgen.
* Enable 'secure' option for pwgen
* root: make global email settings configurable
* stages/email: add use_global_settings
* stages/email: add test_email command to test email sending
* stages/email: update email template
* stages/email: simplify email template path
* stages/email: add support for user-supplied email templates
* stages/email: add tests for sending and templates
* stages/email: only add custom template if permissions are correct
* docs: add custom email template docs
* root: add /templates volume in docker-compose by default
* stages/email: fix form not allowing custom templates
* stages/email: use relative path for custom templates
* stages/email: check if all templates exist on startup, reset
* docs: add global email docs for docker-compose
* helm: add email config to helm chart
* helm: load all secrets with env prefix
* helm: move s3 and smtp secret to secret
* stages/email: fix test for relative name
* stages/email: add argument to send email from existing stage
* stages/email: set uid using slug of message id
* stages/email: ensure template validation ignores migration runs
* docs: add email troubleshooting docs
* stages/email: fix long task_name breaking task list
