Allow to set "domain-suffix-match" in Wi-Fi settings

Summary:
This concerns Wi-Fi settings of enterprise WPA/WPA2:
* TLS
* tunneled TLS
* PEAP

Requires commit `Support "domain-suffix-match" in Security8021xSetting` in `networkmanager-qt` (https://phabricator.kde.org/D8402).

Test Plan:
1. ApplySupport "domain-suffix-match" in Security8021xSetting` in `networkmanager-qt` as well
2. Open connection settings
3. Select Wi-Fi connection
4. Configure domain under enterprise security settings
5. Apply
5. Open related config file, eg. `/etc/NetworkManager/system-connections/eduroam`
6. Check whether "domain-suffix-match" is set correctly.

BTW: To use the development build of the kcm module one must set `QT_PLUGIN_PATH` to the directory where `kcm_networkmanagement.so` has been installed. Then it can be tested by executing eg. `kcmshell5 --desktopfile /devel/stuff/share/kservices5/plasma-applet-org.kde.plasma.networkmanagement.desktop kcm_networkmanagement`.

Reviewers: #plasma, jgrulich

Reviewed By: jgrulich

Subscribers: jgrulich, ngraham, plasma-devel

Tags: #plasma

Differential Revision: https://phabricator.kde.org/D8405