Removes now redundant face_at checks, allows observers to face.

Was initially an attempt to fix lying mobs being unable to change facing to but https://github.com/Baystation12/Baystation12/blob/master/code/modules/mob/mob.dm#L764 complicates this.
Merge pull request #7424 from PsiOmegaDelta/Examinate

Allows observers to face what they examine/point at.