Prevent user from entering incorrect characters in Live Notifications channels list (#3715)

Co-authored-by: Sidd <iProdigy@users.noreply.github.com>
Co-authored-by: Rasmus Karlsson <rasmus.karlsson@pajlada.com>

src/widgets/helper/EditableModelView.hpp

@@ -16,6 +16,7 @@ public:
     EditableModelView(QAbstractTableModel *model, bool movable = true);
 
     void setTitles(std::initializer_list<QString> titles);
+    void setValidationRegexp(QRegularExpression regexp);
 
     QTableView *getTableView();
     QAbstractTableModel *getModel();