Send forgotPassword and verifyEmail as Plain Text

[ainsleyclark]

It would be good if we could send Plain Text as well as HTML in the auth email hooks to avoid spam filtering:

forgotPassword?: {
    /**
     * The number of milliseconds that the forgot password token should be valid for.
     * @default 3600000 // 1 hour
     */
    expiration?: number;
    generateEmailHTML?: GenerateForgotPasswordEmailHTML;
    generateEmailSubject?: GenerateForgotPasswordEmailSubject;
};

Mentioned on Discord