[libcalamares] Add accessors for TZ data and region in the model

It's convenient when e.g. QComboBox::currentData() gets the key
"automatically", and the default role for that method is UserRole,
so let the value of KeyRole overlap.

src/libcalamares/locale/TimeZone.cpp

@@ -262,15 +262,17 @@ ZonesModel::data( const QModelIndex& index, int role ) const
     }
 
     const auto* zone = m_private->m_zones[ index.row() ];
-    if ( role == NameRole )
+    switch ( role )
     {
+    case NameRole:
         return zone->tr();
-    }
-    if ( role == KeyRole )
-    {
+    case KeyRole:
         return zone->key();
+    case RegionRole:
+        return zone->region();
+    default:
+        return QVariant();
     }
-    return QVariant();
 }
 
 QHash< int, QByteArray >

src/libcalamares/locale/TimeZone.h

@@ -54,11 +54,18 @@ public:
                   const QString& country,
                   double latitude,
                   double longitude );
+    TimeZoneData( const TimeZoneData& ) = delete;
+    TimeZoneData( TimeZoneData&& ) = delete;
+
     QString tr() const override;
 
     QString region() const { return m_region; }
     QString zone() const { return key(); }
 
+    QString country() const { return m_country; }
+    double latitude() const { return m_latitude; }
+    double longitude() const { return m_longitude; }
+
 private:
     QString m_region;
     QString m_country;
@@ -80,7 +87,7 @@ public:
     enum Roles
     {
         NameRole = Qt::DisplayRole,
-        KeyRole = Qt::UserRole + 1
+        KeyRole = Qt::UserRole  // So that currentData() will get the key
     };
 
     RegionsModel( QObject* parent = nullptr );
@@ -103,7 +110,8 @@ public:
     enum Roles
     {
         NameRole = Qt::DisplayRole,
-        KeyRole = Qt::UserRole + 1
+        KeyRole = Qt::UserRole,  // So that currentData() will get the key
+        RegionRole = Qt::UserRole + 1
     };
 
     ZonesModel( QObject* parent = nullptr );