Configure SMTP for Lightdash email notifications

This is a reference to all the SMTP environment variables that can be used to configure a Lightdash email client.

Variable	Description	Required?	Default
EMAIL_SMTP_HOST	Hostname of email server	✅
EMAIL_SMTP_PORT	Port of email server		587
EMAIL_SMTP_SECURE	Secure connection		true
EMAIL_SMTP_USER	Auth user	✅
EMAIL_SMTP_PASSWORD	Auth password	[1]
EMAIL_SMTP_ACCESS_TOKEN	Auth access token for Oauth2 authentication	[1]
EMAIL_SMTP_ALLOW_INVALID_CERT	Allow connection to TLS server with self-signed or invalid TLS certificate		false
EMAIL_SMTP_SENDER_EMAIL	The email address that sends emails	✅
EMAIL_SMTP_SENDER_NAME	The name of the email address that sends emails		Lightdash

[1] EMAIL_SMTP_PASSWORD or EMAIL_SMTP_ACCESS_TOKEN needs to be provided