Multiple-Choice Matrix - Use choices in multiple columns - Add or remove columns on design surface when `showInMultipleColumns: "true"`

[JaneSjs]

Original issue: T12622 - Is it possible to have 'matrix' question type to have cellType 'checkbox' without the additional features of 'matrixdropdown' and 'matrixdynamic'? https://surveyjs.answerdesk.io/internal/ticket/details/T12622

In a Single-Choice Matrix, users can quickly add or remove columns on design surface:

https://user-images.githubusercontent.com/22372972/232034355-76db7d15-7f5c-4d7a-a02c-047219ad9be8.mp4

If you configure a Multiple-Choice Matrix and use a Checkbox column in multiple columns, it is impossible to add or remove columns in the same way:

https://user-images.githubusercontent.com/22372972/232034650-263ce5ca-e65e-4a01-873c-0555c47e2c79.mp4

Suggestion: add an option to add or remove columns on design surface.