Pillar / Monument cleanup.

Prevent Iberian players from covering their entire territory with the attack bonus giving monument as proposed by mimo.
Indirect aura range indication with the build restrictions for the trade bonus yielding mauryan pillar.
Disable capturing of mauryan pillar equally to the iberian one following rP18024 (so that the entire territory doesn't switch ownership quickly).
Add the missing name for the mauryan pillar, so that the aura bonus tooltip shows up, as reported by Grugnas.

Differential Revision: https://code.wildfiregames.com/D196
Reviewed By: Grugnas
Fixes #4412