Use email_address_with_name helper in user_mailer

[mguidetti]

This change adds the ActionMailer::Base#email_address_with_name helper added in Rails 6 to UserMailer so that customer names with special characters are escaped.

Previously, the mailer could throw a Net::SMTPSyntaxError error if customer names had special characters. I ran across this with a customer who had a comma and period in their name. (eg: "Business Name, Inc.")

[mguidetti]

Ah, my mistake. I thought this helper was added in 6.0, but looks like it was a 6.1 addition. Will look for a 6.0 compatible solution

[mguidetti]

I extracted out rails 6.1's email_address_with_name helper here so that the gem can still be compatible with 6.0

[excid3]

Thanks for this!