Plugins: Add skeleton for new ExtensionManager plugin

This initial commit is merely a mockup of a ExtensionManager concept.

Change-Id: I19b2285667678a86097c043cc27a554545559eff
Reviewed-by: Alessandro Portale <alessandro.portale@qt.io>
Reviewed-by: hjk <hjk@qt.io>

src/plugins/extensionmanager/extensionmanagerplugin.cpp

@@ -0,0 +1,91 @@
+// Copyright (C) 2023 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0-only WITH Qt-GPL-exception-1.0
+
+#include "extensionmanagertr.h"
+
+#include "extensionmanagerconstants.h"
+#include "extensionmanagerwidget.h"
+
+#include <coreplugin/actionmanager/actioncontainer.h>
+#include <coreplugin/actionmanager/actionmanager.h>
+#include <coreplugin/actionmanager/command.h>
+#include <coreplugin/coreconstants.h>
+#include <coreplugin/icontext.h>
+#include <coreplugin/icore.h>
+#include <coreplugin/imode.h>
+#include <coreplugin/modemanager.h> // TODO: Remove!
+
+#include <extensionsystem/iplugin.h>
+#include <extensionsystem/pluginspec.h>
+
+#include <utils/icon.h>
+#include <utils/layoutbuilder.h>
+#include <utils/styledbar.h>
+
+#include <QAction>
+#include <QMainWindow>
+
+using namespace ExtensionSystem;
+using namespace Core;
+using namespace Utils;
+
+namespace ExtensionManager::Internal {
+
+class ExtensionManagerMode final : public IMode
+{
+public:
+    ExtensionManagerMode()
+    {
+        setObjectName("ExtensionManagerMode");
+        setId(Constants::C_EXTENSIONMANAGER);
+        setContext(Context(Constants::MODE_EXTENSIONMANAGER));
+        setDisplayName(Tr::tr("Extensions"));
+        const Icon FLAT({{":/extensionmanager/images/mode_extensionmanager_mask.png",
+                          Theme::IconsBaseColor}});
+        const Icon FLAT_ACTIVE({{":/extensionmanager/images/mode_extensionmanager_mask.png",
+                                 Theme::IconsModeWelcomeActiveColor}});
+        setIcon(Utils::Icon::modeIcon(FLAT, FLAT, FLAT_ACTIVE));
+        setPriority(72);
+
+        using namespace Layouting;
+        auto widget = Column {
+            new StyledBar,
+            new ExtensionManagerWidget,
+            noMargin, spacing(0),
+        }.emerge();
+
+        setWidget(widget);
+    }
+
+    ~ExtensionManagerMode() { delete widget(); }
+};
+
+class ExtensionManagerPlugin final : public ExtensionSystem::IPlugin
+{
+    Q_OBJECT
+    Q_PLUGIN_METADATA(IID "org.qt-project.Qt.QtCreatorPlugin" FILE "ExtensionManager.json")
+
+public:
+    ~ExtensionManagerPlugin() final
+    {
+        delete m_mode;
+    }
+
+    void initialize() final
+    {
+        m_mode = new ExtensionManagerMode;
+    }
+
+    bool delayedInitialize() final
+    {
+        ModeManager::activateMode(m_mode->id()); // TODO: Remove!
+        return true;
+    }
+
+private:
+    ExtensionManagerMode *m_mode = nullptr;
+};
+
+} // ExtensionManager::Internal
+
+#include "extensionmanagerplugin.moc"