[libcalamaresui] Move message- and clipboard handling

- The Paste API promises just a (string) URL back, not
  a whole message, so return just the URL from the
  abstract API and the concrete (fiche) implementation.
- Set clipboard contents from the UI
- Build (translated) message in the UI code

src/libcalamaresui/ViewManager.cpp

@@ -27,6 +27,7 @@
 
 #include <QApplication>
 #include <QBoxLayout>
+#include <QClipboard>
 #include <QFile>
 #include <QMessageBox>
 #include <QMetaObject>
@@ -189,16 +190,26 @@ ViewManager::onInstallationFailed( const QString& message, const QString& detail
     connect( msgBox, &QMessageBox::buttonClicked, [msgBox]( QAbstractButton* button ) {
         if ( msgBox->buttonRole( button ) == QMessageBox::ButtonRole::YesRole )
         {
-            QString pasteUrlMsg = CalamaresUtils::Paste::doLogUpload( msgBox );
-
-            QString pasteUrlTitle = tr( "Install Log Paste URL" );
-            if ( pasteUrlMsg.isEmpty() )
+            QString pasteUrl = CalamaresUtils::Paste::doLogUpload( msgBox );
+            QString pasteUrlMessage;
+            if ( pasteUrl.isEmpty() )
+            {
+                pasteUrlMessage = tr( "The upload was unsuccessful. No web-paste was done." );
+            }
+            else
             {
-                pasteUrlMsg = tr( "The upload was unsuccessful. No web-paste was done." );
+                QClipboard* clipboard = QApplication::clipboard();
+                clipboard->setText( pasteUrl, QClipboard::Clipboard );
+
+                if ( clipboard->supportsSelection() )
+                {
+                    clipboard->setText( pasteUrl, QClipboard::Selection );
+                }
+                QString pasteUrlFmt = tr( "Install log posted to\n\n%1\n\nLink copied to clipboard" );
+                pasteUrlMessage = pasteUrlFmt.arg( pasteUrl );
             }
 
-            // TODO: make the URL clickable, or copy it to the clipboard automatically
-            QMessageBox::critical( nullptr, pasteUrlTitle, pasteUrlMsg );
+            QMessageBox::critical( nullptr, tr( "Install Log Paste URL" ), pasteUrlMessage );
         }
         QApplication::quit();
     } );

src/libcalamaresui/utils/Paste.cpp

@@ -12,10 +12,7 @@
 #include "Branding.h"
 #include "utils/Logger.h"
 
-#include <QApplication>
-#include <QClipboard>
 #include <QFile>
-#include <QStringList>
 #include <QTcpSocket>
 #include <QUrl>
 
@@ -82,29 +79,16 @@ ficheLogUpload( const QUrl& serverUrl, QObject* parent )
     socket->close();
 
     QUrl pasteUrl = QUrl( QString( responseText ).trimmed(), QUrl::StrictMode );
-    QString pasteUrlStr = pasteUrl.toString();
-
-    QString pasteUrlFmt = parent->tr( "Install log posted to\n\n%1\n\nLink copied to clipboard" );
-    QString pasteUrlMsg = pasteUrlFmt.arg( pasteUrlStr );
-
     if ( pasteUrl.isValid() && pasteUrl.host() == serverUrl.host() )
     {
-        QClipboard* clipboard = QApplication::clipboard();
-        clipboard->setText( pasteUrlStr, QClipboard::Clipboard );
-
-        if ( clipboard->supportsSelection() )
-        {
-            clipboard->setText( pasteUrlStr, QClipboard::Selection );
-        }
+        cDebug() << Logger::SubEntry << "Paste server results:" << pasteUrl;
+        return pasteUrl.toString();
     }
     else
     {
         cError() << "No data from paste server";
         return QString();
     }
-
-    cDebug() << Logger::SubEntry << "Paste server results:" << pasteUrlMsg;
-    return pasteUrlMsg;
 }
 
 QString