qmlpreview: prepare plugin to have an external client

- export the plugin andd add client creator API to be able to implement
  external debugtranslationclients
- use the private/qqmldebugtranslationprotocol_p.h from Qt5::QmlDebugPrivate
- have a basic client implementation which cares about changing language
- remove out of date elide warning implementation
- remove old ui
- remove the menu entry

The old client implementation is incompatible with the will be introduced
service and there was never an officially released compatible service.
Therefore we can remove the old client implementation without causing
any harm.

Change-Id: I26b5e8a99ba30ae6377443b3fffb05901b1cac28
Reviewed-by: Tim Jenssen <tim.jenssen@qt.io>

src/plugins/qmlpreview/qmlpreviewconnectionmanager.cpp

@@ -40,6 +40,9 @@ QmlPreviewConnectionManager::QmlPreviewConnectionManager(QObject *parent) :
     QmlDebug::QmlDebugConnectionManager(parent)
 {
     setTarget(nullptr);
+    m_createDebugTranslationClientMethod = [](QmlDebug::QmlDebugConnection *connection) {
+        return std::make_unique<QmlPreview::QmlDebugTranslationClient>(connection);
+    };
 }
 
 QmlPreviewConnectionManager::~QmlPreviewConnectionManager() = default;
@@ -66,6 +69,11 @@ void QmlPreviewConnectionManager::setFpsHandler(QmlPreviewFpsHandler fpsHandler)
     m_fpsHandler = fpsHandler;
 }
 
+void QmlPreviewConnectionManager::setQmlDebugTranslationClientCreator(QmlDebugTranslationClientCreator creator)
+{
+    m_createDebugTranslationClientMethod = creator;
+}
+
 void QmlPreviewConnectionManager::createClients()
 {
     createPreviewClient();
@@ -113,9 +121,9 @@ QUrl QmlPreviewConnectionManager::findValidI18nDirectoryAsUrl(const QString &loc
 
 void QmlPreviewConnectionManager::createDebugTranslationClient()
 {
-    m_qmlDebugTranslationClient = new QmlDebugTranslationClient(connection());
+    m_qmlDebugTranslationClient = m_createDebugTranslationClientMethod(connection());
     connect(this, &QmlPreviewConnectionManager::language,
-                     m_qmlDebugTranslationClient, [this](const QString &locale) {
+                     m_qmlDebugTranslationClient.get(), [this](const QString &locale) {
         m_lastUsedLanguage = locale;
         // findValidI18nDirectoryAsUrl does not work if we didn't load any file
         // service expects a context URL.
@@ -124,10 +132,7 @@ void QmlPreviewConnectionManager::createDebugTranslationClient()
             m_qmlDebugTranslationClient->changeLanguage(findValidI18nDirectoryAsUrl(locale), locale);
         }
     });
-    connect(this, &QmlPreviewConnectionManager::changeElideWarning,
-            m_qmlDebugTranslationClient, &QmlDebugTranslationClient::changeElideWarning);
-
-    connect(m_qmlDebugTranslationClient.data(), &QmlDebugTranslationClient::debugServiceUnavailable,
+    connect(m_qmlDebugTranslationClient.get(), &QmlDebugTranslationClient::debugServiceUnavailable,
                      this, []() {
         QMessageBox::warning(Core::ICore::dialogParent(), "Error connect to QML DebugTranslation service",
                              "QML DebugTranslation feature is not available for this version of Qt.");
@@ -260,7 +265,7 @@ void QmlPreviewConnectionManager::clearClient(QObject *client)
 void QmlPreviewConnectionManager::destroyClients()
 {
     clearClient(m_qmlPreviewClient);
-    clearClient(m_qmlDebugTranslationClient);
+    clearClient(m_qmlDebugTranslationClient.release());
     m_fileSystemWatcher.removeFiles(m_fileSystemWatcher.files());
     QTC_ASSERT(m_fileSystemWatcher.directories().isEmpty(),
                m_fileSystemWatcher.removeDirectories(m_fileSystemWatcher.directories()));