[applets/digital-clock] Switch timezones by clicking on them in the popup

Summary:
This patch allows you to switch the timezone by clicking on your desired one in the
applet's expanded representation. This is much simpler than the mouse-wheel-based UI and
does not need a config setting to turn it on or off.

Test Plan: {F8183863}

Reviewers: #vdg, #plasma, jriddell, cblack

Reviewed By: #vdg, #plasma, cblack

Subscribers: plasma-devel

Tags: #plasma

Maniphest Tasks: T9222

Differential Revision: https://phabricator.kde.org/D28133

applets/digital-clock/package/contents/ui/CalendarView.qml

@@ -431,6 +431,12 @@ Item {
                         id: listItem
                         readonly property bool isCurrentTimeZone: modelData === plasmoid.configuration.lastSelectedTimezone
 
+                        MouseArea {
+                            anchors.fill: parent
+                            cursorShape: Qt.PointingHandCursor
+                            onClicked: plasmoid.configuration.lastSelectedTimezone = modelData
+                        }
+
                         ColumnLayout {
 
                             width: clocksList.width