feat: add poll and prediction commands for broadcasters (#6583)

Reviewed-by: nerix <nero.9@hotmail.de>
Reviewed-by: pajlada <rasmus.karlsson@pajlada.com>

src/controllers/commands/builtin/twitch/Prediction.hpp

@@ -0,0 +1,16 @@
+#pragma once
+
+class QString;
+
+namespace chatterino {
+
+struct CommandContext;
+
+}  // namespace chatterino
+
+namespace chatterino::commands {
+
+/// /prediction
+QString createPrediction(const CommandContext &ctx);
+
+}  // namespace chatterino::commands