LibGUI: Take ProcessManager's process view and turn it into GTableView.

Make it sufficiently generic that it can be reused for any table data. :^)

LibGUI/GTableModel.cpp

@@ -0,0 +1,33 @@
+#include <LibGUI/GTableModel.h>
+#include <LibGUI/GTableView.h>
+
+GTableModel::GTableModel()
+{
+}
+
+GTableModel::~GTableModel()
+{
+}
+
+void GTableModel::register_view(Badge<GTableView>, GTableView& view)
+{
+    m_views.set(&view);
+}
+
+void GTableModel::unregister_view(Badge<GTableView>, GTableView& view)
+{
+    m_views.remove(&view);
+}
+
+void GTableModel::for_each_view(Function<void(GTableView&)> callback)
+{
+    for (auto* view : m_views)
+        callback(*view);
+}
+
+void GTableModel::did_update()
+{
+    for_each_view([] (GTableView& view) {
+        view.did_update_model();
+    });
+}