Ubuntu: Smtp settings

Implemented SmtpManager class to store smtp settings

SmtpSettings page.qml only shows relevant input fields for each MSA Connection method

Default ports are tested and removed knowlege of default ports in QML. A warning
is shown if ports are not the default for the connection method

REVIEW: 117588

Change OutgoingPage of the desktop settings dialog to use SmtpAccountManager

Also changing the UI to choose submission type via Method and Encryption combo box's