feat: add initial experimental Twitch Eventsub support (#5837)

Co-authored-by: nerix <nerixdev@outlook.de>

lib/twitch-eventsub-ws/ast/lib/tests/resources/string.hpp

@@ -0,0 +1,10 @@
+#include <optional>
+#include <string>
+#include <vector>
+
+struct String {
+    std::string a;
+    const std::string b;
+    std::vector<std::string> c;
+    std::optional<std::string> d;
+};