SMTP refactor

• always show test configuration button
• if current user does not have email, disable button and show tooltip explaining why on hover
• test configuration will accept current config from the form and attempt to send email using the temporary config, instead of using saved config
• send test mail after saving config
• update email validation rule to convert to punycode and send as punycode to backend, then perform the conversion back
• host and sender fields should validate domain names