Enhance Gmail Support

[altsalt]

Description

While there is a configuration for Gmail accounts (e.g., accounts.email.accounts.<name>.flavor), it does not enforce OAuth2 as the authentication mechanism, a requirement for Google accounts.

For Thunderbird, this is handled with the following block:

accounts.email.accounts.<name>.thunderbird.settings = id: {
  "mail.smtpserver.smtp_${id}.authMethod" = 10;
  "mail.server.server_${id}.authMethod" = 10;
};

I'm not sure if there is a better way to do this, or one that is not tied to a specific client. I also wonder whether adding particular settings for clients that are not being used would cause any issues.

It appears that there was a related development effort which has been set aside due to availability: https://github.com/nix-community/home-manager/pull/4219