* Using MailKit instead of SmtpClient
* Removing 2 more references to System.Net.Http that we hopefully don't need at all anymore
* Attempting to fix Razor compilation warning about Orchard.Email's reference to System.Net.Http
* Improving SmtpSettings.cshtml a bit (port number restrictions, user name box width)
* Fixing encription method is not persisted
* Adding migration step to migrate from EnableSsl to EncryptionMethod in SmtpSettingsPart
* Code styling/simplifications
* Using infoset default values instead of Migrations to keep SSL settings when upgrading to MailKit
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Co-authored-by: Lombiq <github@lombiq.com>
Co-authored-by: Benedek Farkas <benedek.farkas@lombiq.com>
