[welcome] Provide API for updating the country

- Changing country will pre-select the language most likely
   for that country (it doesn't, yet, since we don't have the data).

src/modules/welcome/WelcomeViewStep.cpp

@@ -126,9 +126,11 @@ WelcomeViewStep::setConfigurationMap( const QVariantMap& configurationMap )
             CalamaresUtils::getString( geoip, "url" ),
             CalamaresUtils::getString( geoip, "selector" ) );
         auto* future = new FWString();
-        connect( future, &FWString::finished, [f=future, h=handler]()
+        connect( future, &FWString::finished, [view=this, f=future, h=handler]()
         {
-            cDebug() << "GeoIP result for welcome=" << f->future().result();
+            QString countryResult = f->future().result();
+            cDebug() << "GeoIP result for welcome=" << countryResult;
+            view->setCountry( countryResult );
             f->deleteLater();
             delete h;
         } );
@@ -136,7 +138,20 @@ WelcomeViewStep::setConfigurationMap( const QVariantMap& configurationMap )
     }
 }
 
-Calamares::RequirementsList WelcomeViewStep::checkRequirements()
+Calamares::RequirementsList
+WelcomeViewStep::checkRequirements()
 {
     return m_requirementsChecker->checkRequirements();
 }
+
+void
+WelcomeViewStep::setCountry( const QString& countryCode )
+{
+    if ( countryCode.length() != 2 )
+    {
+        cDebug() << "Unusable country code" << countryCode;
+        return;
+    }
+
+    cDebug() << "TODO: update country" << countryCode;
+}

src/modules/welcome/WelcomeViewStep.h

@@ -54,6 +54,13 @@ public:
 
     void setConfigurationMap( const QVariantMap& configurationMap ) override;
 
+    /** @brief Sets the country that Calamares is running in.
+     *
+     * This (ideally) sets up language and locale settings that are right for
+     * the given 2-letter country code.
+     */
+    void setCountry( const QString& );
+
     Calamares::RequirementsList checkRequirements() override;
 
 private: