Is your feature request related to a problem? Please describe.
The pillars and pavers have directional facing options, but their slap counterparts don't (see green & red arrows in picture below).
Which, sure, you can work around it by using the full blocks instead, but you usually went for the slabs for a reason (like preserving resources/space, height variation, etc.)

Describe the solution you'd like
Being able to place them in both directions (west-east/south-north) based on placement - facing whatever direction the side of a block you're placing it next to is, or the player's view direction when placing it on the ground/ceiling.

Describe alternatives you've considered
Alternative (probably easier to implement) would be added variants of these blocks in these directions, so you'd have "Stone Column Slab" and "Stone Column Slab (90° Rotated)".

Additional context

Duplicate of #11
Already a planned feature for the future - hopefully :)