Allow the Editor choose whether to show 1 Row, 2 Rows or All of the Posts by default

This would display 4/8/All on L/XL screens and 3/6/All on M screens.

for the Load More button:
on L/XL, Load More should reveal 4 additional Posts each time it's clicked
on M, Load More should reveal 3 additional Posts each time it's clicked

_ Please have this block behaviour mimic that of the [Take Action covers|https://jira.greenpeace.org/browse/PLANET-1633
] _

vromuald let's discuss the behaviour for this block on S screens.
currently, it's a swipe. but there's no way to load more beyond the default of 4 Posts.
e.g. www.greenpeace.org/greece/apologismoi