Support hiding the trailing / final newline

[ModProg]

#8157 added insert-final-newline, something that I personally like, but I prefer the way vim handles it, by hiding this trailing newline.

I would like to have this trailing newline not show up as an additional empty line. (this could/should be configurable)

[pascalkuthe]

This is something we rejected repeatedly and orthogonal to that option. It's an intentional part of helix editing model that the last line is selectable.