[locale] Set *locale* GS key when needed

The code path for setting the locale / language automatically
emits currentLanguageStatusChanged(), but the code that updates
GS connects to currentLanguageCodeChaged(). This was altered in
the 3.2.28 release cycle. Since then, automcatic locale selection
wasn't setting *locale* in GS, so that a click-through kind of
locale selection would not set it; then the packages module
has no *locale* setting for localization packages.

The combination of status and code signals (machine- and human-
readable) is ok. Introduce a setter to the language that does
the necessary signalling, so that setting the language automatically
also DTRT.

FIXES #1671

src/modules/locale/Config.cpp

@@ -259,8 +259,7 @@ Config::setCurrentLocation( const CalamaresUtils::Locale::TimeZoneData* location
         auto newLocale = automaticLocaleConfiguration();
         if ( !m_selectedLocaleConfiguration.explicit_lang )
         {
-            m_selectedLocaleConfiguration.setLanguage( newLocale.language() );
-            emit currentLanguageStatusChanged( currentLanguageStatus() );
+            setLanguage( newLocale.language() );
         }
         if ( !m_selectedLocaleConfiguration.explicit_lc )
         {
@@ -302,11 +301,20 @@ Config::localeConfiguration() const
 void
 Config::setLanguageExplicitly( const QString& language )
 {
-    m_selectedLocaleConfiguration.setLanguage( language );
     m_selectedLocaleConfiguration.explicit_lang = true;
+    setLanguage( language );
+}
+
+void
+Config::setLanguage( const QString& language )
+{
+    if ( language != m_selectedLocaleConfiguration.language() )
+    {
+        m_selectedLocaleConfiguration.setLanguage( language );
 
-    emit currentLanguageStatusChanged( currentLanguageStatus() );
-    emit currentLanguageCodeChanged( currentLanguageCode() );
+        emit currentLanguageStatusChanged( currentLanguageStatus() );
+        emit currentLanguageCodeChanged( currentLanguageCode() );
+    }
 }
 
 void

src/modules/locale/Config.h

@@ -95,6 +95,8 @@ private:
     }
 
 public Q_SLOTS:
+    /// Set the language, but do not mark it as user-choice
+    void setLanguage( const QString& language );
     /// Set a language by user-choice, overriding future location changes
     void setLanguageExplicitly( const QString& language );
     /// Set LC (formats) by user-choice, overriding future location changes