make helper function for trimming a twitch channel name from irc

src/providers/twitch/twitchhelpers.hpp

@@ -0,0 +1,13 @@
+#pragma once
+
+#include <QString>
+
+namespace chatterino {
+namespace providers {
+namespace twitch {
+
+bool TrimChannelName(const QString &channelName, QString &outChannelName);
+
+}  // namespace twitch
+}  // namespace providers
+}  // namespace chatterino