Support SAE in securityTypeFromConnectionSetting

Summary: Allow SAE to be returned from securityTypeFromConnectionSetting.

Test Plan: Not visible on its own. Intended to work with another plasma-nm change.

Reviewers: jgrulich

Reviewed By: jgrulich

Subscribers: kde-frameworks-devel

Tags: Frameworks

Differential Revision: https://phabricator.kde.org/D27665