feat: Allow negation of search predicates (#4207)

Co-authored-by: Rasmus Karlsson <rasmus.karlsson@pajlada.com>
closes https://github.com/Chatterino/chatterino2/issues/3998

src/messages/search/SubtierPredicate.hpp

@@ -16,10 +16,12 @@ public:
     /**
      * @brief Create an SubtierPredicate with a list of subtiers to search for.
      *
-     * @param subtiers a list of subtiers that a message should contain 
+     * @param subtiers one or more comma-separated subtiers that the message should contain
+     * @param negate when set, excludes messages containing selected subtiers from results
      */
-    SubtierPredicate(const QStringList &subtiers);
+    SubtierPredicate(const QString &subtiers, bool negate);
 
+protected:
     /**
      * @brief Checks whether the message contains any of the subtiers passed
      *        in the constructor.
@@ -28,7 +30,7 @@ public:
      * @return true if the message contains a subtier listed in the specified subtiers,
      *         false otherwise
      */
-    bool appliesTo(const Message &message) override;
+    bool appliesToImpl(const Message &message) override;
 
 private:
     /// Holds the subtiers that will be searched for