Initial backend test for user-based data/customizations (#4144)

Right now only support for colors and no real UX, idea is to test it & allow the idea to grow while figuring out the UX

src/util/serialize/Container.hpp

@@ -0,0 +1,51 @@
+#pragma once
+
+#include <QString>
+#include <pajlada/serialize.hpp>
+
+#include <unordered_map>
+
+namespace pajlada {
+
+template <typename ValueType, typename RJValue>
+struct Serialize<std::unordered_map<QString, ValueType>, RJValue> {
+    static RJValue get(const std::unordered_map<QString, ValueType> &value,
+                       typename RJValue::AllocatorType &a)
+    {
+        RJValue ret(rapidjson::kObjectType);
+
+        for (auto it = value.begin(); it != value.end(); ++it)
+        {
+            detail::AddMember<ValueType, RJValue>(ret, it->first.toUtf8(),
+                                                  it->second, a);
+        }
+
+        return ret;
+    }
+};
+
+template <typename ValueType, typename RJValue>
+struct Deserialize<std::unordered_map<QString, ValueType>, RJValue> {
+    static std::unordered_map<QString, ValueType> get(const RJValue &value,
+                                                      bool *error = nullptr)
+    {
+        std::unordered_map<QString, ValueType> ret;
+
+        if (!value.IsObject())
+        {
+            PAJLADA_REPORT_ERROR(error)
+            return ret;
+        }
+
+        for (typename RJValue::ConstMemberIterator it = value.MemberBegin();
+             it != value.MemberEnd(); ++it)
+        {
+            ret.emplace(it->name.GetString(),
+                        Deserialize<ValueType, RJValue>::get(it->value, error));
+        }
+
+        return ret;
+    }
+};
+
+}  // namespace pajlada