Add support for FastMail accounts

FastMail is a paid-for email service provider: “As a paid service, we only serve you, our customer. This means we have no split loyalties, no mining of your personal data, no sharing it with third parties, and no ads, ever.”

It's also the email service I use.

Geary has special support for surveillance-based email services from Google, Yahoo, and Microsoft but doesn't support an ethical email service provider like FastMail. It should and it should give it preference in the list (we should be advocating and supporting services that do not violate people's human rights).

Special support for FastMail should be added and FastMail should be listed above surveillance-based email services.