refactor(new_editor/app): reorganize host structure and add smoke test

new_editor/app/Support/StringEncoding.h

@@ -0,0 +1,46 @@
+#pragma once
+
+#include <string>
+#include <string_view>
+
+#include <windows.h>
+
+namespace XCEngine::UI::Editor::Support {
+
+inline std::string WideToUtf8(std::wstring_view text) {
+    if (text.empty()) {
+        return {};
+    }
+
+    const int requiredBytes = WideCharToMultiByte(
+        CP_UTF8,
+        0,
+        text.data(),
+        static_cast<int>(text.size()),
+        nullptr,
+        0,
+        nullptr,
+        nullptr);
+    if (requiredBytes <= 0) {
+        return {};
+    }
+
+    std::string utf8(static_cast<std::size_t>(requiredBytes), '\0');
+    const int convertedBytes = WideCharToMultiByte(
+        CP_UTF8,
+        0,
+        text.data(),
+        static_cast<int>(text.size()),
+        utf8.data(),
+        requiredBytes,
+        nullptr,
+        nullptr);
+    if (convertedBytes <= 0) {
+        return {};
+    }
+
+    utf8.resize(static_cast<std::size_t>(convertedBytes));
+    return utf8;
+}
+
+} // namespace XCEngine::UI::Editor::Support