Inspector: Show remote object properties in a table view

This patch expands the object model of this program quite a bit.
We now have a RemoteProcess object that contains a list of remote root
RemoteObject objects.

The RemoteProcess vends a RemoteObjectGraphModel&, and indices in that
model have internal_data() pointing to a corresponding RemoteObject.
RemoteObjects in turn vend a RemoteObjectPropertyModel&, which is what
we use to show the object properties.

This is pretty cool :^)

DevTools/Inspector/RemoteObjectPropertyModel.cpp

@@ -0,0 +1,46 @@
+#include "RemoteObjectPropertyModel.h"
+#include "RemoteObject.h"
+
+RemoteObjectPropertyModel::RemoteObjectPropertyModel(RemoteObject& object)
+    : m_object(object)
+{
+}
+
+int RemoteObjectPropertyModel::row_count(const GModelIndex&) const
+{
+    return m_properties.size();
+}
+
+String RemoteObjectPropertyModel::column_name(int column) const
+{
+    switch (column) {
+    case Column::Name:
+        return "Name";
+    case Column::Value:
+        return "Value";
+    }
+    ASSERT_NOT_REACHED();
+}
+
+GVariant RemoteObjectPropertyModel::data(const GModelIndex& index, Role role) const
+{
+    auto& property = m_properties[index.row()];
+    if (role == Role::Display) {
+        switch (index.column()) {
+        case Column::Name:
+            return property.name;
+        case Column::Value:
+            return property.value;
+        }
+    }
+    return {};
+}
+
+void RemoteObjectPropertyModel::update()
+{
+    m_properties.clear();
+    m_object.json.for_each_member([this](auto& name, auto& value) {
+        m_properties.append({ name, value });
+    });
+    did_update();
+}