Support SMTP servers with no username/password

### Current Behavior

The email service expects a SMTP server to always have a username/password.

It is possible to setup a SMTP server without the need to authenticate

### Expected Behavior

Allow passing no username/password to mail library

### Steps To Reproduce

Generate a helm values file with no smtp auth section

### Environment

- FlowForge version: 1.4.0
- Node.js version: 16.x
- npm version: 8.x
- Platform/OS: Kubernetes/Linux
- Browser: NA

Start by tracing the email service's SMTP configuration and how Helm values supply authentication settings. Verify that a server with no SMTP username or password can send mail while existing authenticated configurations continue to work.

Written by the indexing model from the issue text.