Move shortcut creation code to its own helper file

src/widgets/helper/shortcut.hpp

@@ -0,0 +1,18 @@
+#pragma once
+
+#include <QShortcut>
+#include <QWidget>
+
+namespace chatterino {
+namespace widgets {
+
+template <typename WidgetType, typename Func>
+inline void CreateShortcut(WidgetType *w, const char *key, Func func)
+{
+    auto s = new QShortcut(QKeySequence(key), w);
+    s->setContext(Qt::WidgetWithChildrenShortcut);
+    QObject::connect(s, &QShortcut::activated, w, func);
+}
+
+}  // namespace widgets
+}  // namespace chatterino