Added in:<channels> search predicate (#2634)

Co-authored-by: pajlada <rasmus.karlsson@pajlada.com>

src/messages/search/ChannelPredicate.cpp

@@ -0,0 +1,23 @@
+#include "messages/search/ChannelPredicate.hpp"
+
+namespace chatterino {
+
+ChannelPredicate::ChannelPredicate(const QStringList &channels)
+    : channels_()
+{
+    // Check if any comma-seperated values were passed and transform those
+    for (const auto &entry : channels)
+    {
+        for (const auto &channel : entry.split(',', QString::SkipEmptyParts))
+        {
+            this->channels_ << channel;
+        }
+    }
+}
+
+bool ChannelPredicate::appliesTo(const Message &message)
+{
+    return channels_.contains(message.channelName, Qt::CaseInsensitive);
+}
+
+}  // namespace chatterino