Use json file based themes instead of code to create them (theme editor + theme mode settings)

common/themes/appearance_tab_widget.h

@@ -0,0 +1,29 @@
+#ifndef APPEARANCE_TAB_WIDGET_H
+#define APPEARANCE_TAB_WIDGET_H
+
+#include <QJsonObject>
+#include <QPointer>
+#include <QWidget>
+#include <functional>
+
+class AppearanceConfiguration;
+class ThemeEditorDialog;
+
+class AppearanceTabWidget : public QWidget
+{
+    Q_OBJECT
+public:
+    explicit AppearanceTabWidget(
+            AppearanceConfiguration *config,
+            std::function<QJsonObject()> currentThemeJson,
+            std::function<void(const QJsonObject &)> applyTheme,
+            QWidget *parent = nullptr);
+
+private:
+    AppearanceConfiguration *config;
+    std::function<QJsonObject()> currentThemeJson;
+    std::function<void(const QJsonObject &)> applyTheme;
+    QPointer<ThemeEditorDialog> themeEditor;
+};
+
+#endif // APPEARANCE_TAB_WIDGET_H