[localeq] Offer a Config setting to set location from region/zone

- already had methods for various kinds of broken-up data, but
  not one for plain "region/zone" strings; having this makes
  it easier for QML to report a zone.
- use the region/zone method from QML, so that clicking on the
  world map updates the actual TZ in Config.

src/modules/locale/Config.cpp

@@ -218,6 +218,15 @@ Config::setCurrentLocation()
     }
 }
 
+void Config::setCurrentLocation(const QString& regionzone)
+{
+    auto r = CalamaresUtils::GeoIP::splitTZString( regionzone );
+    if ( r.isValid() )
+    {
+        setCurrentLocation( r.first, r.second );
+    }
+}
+
 void
 Config::setCurrentLocation( const QString& regionName, const QString& zoneName )
 {

src/modules/locale/Config.h

@@ -92,7 +92,14 @@ public Q_SLOTS:
     /// Set LC (formats) by user-choice, overriding future location changes
     void setLCLocaleExplicitly( const QString& locale );
 
-    /** @brief Sets a location by name
+    /** @brief Sets a location by full name
+     *
+     * @p regionzone should be an identifier from zone.tab, e.g. "Africa/Abidjan",
+     * which is split into regon and zone. Invalid names will **not**
+     * change the actual location.
+     */
+    void setCurrentLocation( const QString& regionzone );
+    /** @brief Sets a location by split name
      *
      * @p region should be "America" or the like, while @p zone
      * names a zone within that region.

src/modules/localeq/Map.qml

@@ -74,6 +74,7 @@ Column {
                 var tz2 = responseJSON.timezoneId
 
                 tzText.text = "Timezone: " + tz2
+                config.setCurrentLocation(tz2)
             }
         }