CSS Grid for columns block

[strarsis]

Is your feature request related to a problem? Please describe.
Using CSS Grid for the core/columns block would make the styles much simpler and easier to customize. Currently, flexbox is used and complicated media queries with margins for emulating gaps between the columns (vertical gaps seem to be missing anyway).

Describe the solution you'd like
Styles using CSS Grid for the core/columns block base styles.

Describe alternatives you've considered
Adjusting existing flexbox styles is very cumbersome and error-prone, especially when it comes to readjusting media queries for switching the columns count.

[ghost]

I agree, especially since it is already being used in the Media/Text block. In my opinion the experience with it is much smoother!

[talldan]

There's lots of discussion about columns over on this issue - #16370.