className doesnt come through on core blocks

[sloyer]

Describe the bug
If you go to the advanced tab of the block and add a Class Name.
The Class Name will not carry over to the block

To Reproduce
Add two columns to the gird, add the Class Name.
When you view on the page, class name does not carry over to the block
Inspect code output on page, no class name is attached

Add a Cover block
Enter class name in advance tab
Inspect code output on page, no class name is attached

Expected behavior
The class name should append to parent div to the block