feat: templated MapEnts dumper (#923)

Relates to https://github.com/Laupetin/OpenAssetTools/issues/626

test/SystemTests/Game/IW4/MapEntsIW4.cpp

@@ -0,0 +1,47 @@
+#include "Game/IW4/Maps/MapEntsDumperIW4.h"
+#include "SearchPath/MockOutputPath.h"
+#include "SearchPath/MockSearchPath.h"
+#include "ZoneLoading.h"
+
+#include <catch2/catch_test_macros.hpp>
+#include <memory>
+#include <string>
+
+using namespace IW4;
+
+namespace
+{
+    TEST_CASE("MapEnts dumper writes entity string (IW4)", "[iw4][mapents][system]")
+    {
+        constexpr auto MAP_ENTS_NAME = "maps/mp/test_map.d3dbsp";
+        char entityString[] = R"({
+"classname" "worldspawn"
+}
+)";
+
+        TriggerModel triggerModel{};
+        Stage stage{};
+        MapEnts mapEnts{};
+        mapEnts.name = MAP_ENTS_NAME;
+        mapEnts.entityString = entityString;
+        mapEnts.numEntityChars = sizeof(entityString);
+        mapEnts.trigger.count = 1;
+        mapEnts.trigger.models = &triggerModel;
+        mapEnts.stages = &stage;
+        mapEnts.stageCount = 1;
+
+        Zone zone("MockZone", 0, GameId::IW4, GamePlatform::PC);
+        zone.m_pools.AddAsset(std::make_unique<XAssetInfo<MapEnts>>(ASSET_TYPE_MAP_ENTS, mapEnts.name, &mapEnts));
+
+        MockSearchPath mockObjPath;
+        MockOutputPath mockOutput;
+        AssetDumpingContext dumpingContext(zone, "", mockOutput, mockObjPath, std::nullopt);
+        map_ents::DumperIW4 dumper;
+        dumper.Dump(dumpingContext);
+
+        const auto* dumpedFile = mockOutput.GetMockedFile("maps/mp/test_map.d3dbsp.ents");
+        REQUIRE(dumpedFile != nullptr);
+        REQUIRE(dumpedFile->m_data.size() == sizeof(entityString) - 1);
+        REQUIRE(dumpedFile->AsString() == entityString);
+    }
+} // namespace