Is your feature request related to a problem? Please describe.
Momently, an individual column can not define specific allowed blocks to be added. Furthermore, newly added columns from the slider in the columns settings also can not only allow certain blocks.

Use case - As a WordPress developer I want to be able to assign allowed blocks for individual columns in my custom block I am developing so I can guide and restrict the user in adding certain blocks.

Describe the solution you'd like
I want to introduce a new attribute called allowedBlocks, which is used to define the allowed blocks in the column(s). Locally, I have made a solution to this problem which locates to PR #18164.

Describe alternatives you've considered
I have considered creating my own column(s) block, which I did not find to be a relevant solution as I think other people could run into this problem as well.