feat: appear as many UIImages as the UIButton answers

[stefaniamak]

Tasks

• [x] add UIImages to new column according to prefab file
• [x] set a default asset for the answer button UIImage
• [x] set a custom asset for the answer button UIImage
• [x] create a binding of answer UIImages visibility and hovering over the answers
• [x] add a new column for the UIImages in the Dialogs module (other than the LAS module https://github.com/Terasology/LightAndShadow/pull/139)
• [x] insert new arrow asset
• [ ] edit answer button's background and font color/shadow - can be done in later PR - WIP https://github.com/Terasology/Dialogs/pull/18

Purpose

Set an arrow asset to appear in the appropriate UIImage next to the hovered UIButton.

How to test

For any module other than LightAndShadow (LaS)

• Start a new game of a module other than LaS, which has a dialogue box and provide answers to choose from
• Open the dialogue box within the game
• Hover over the answer(s) and see if the image appears right before the them
• Your result should look like:

note while testing this myself: the UIButton flickered sometimes, just a little bit slightly from left to right. Unsure of its causes.

concerns: I am worried that if some another module Overrides the Dialog box, then there is going to be errors when trying to activate the box within the game.

For LAS

• Check https://github.com/Terasology/LightAndShadowResources/pull/53
• Check https://github.com/Terasology/LightAndShadow/pull/139
• Start a LAS game
• Talk to The Fool NPC
• Hover over the answer(s)
• See the image/s next to the answer button/s like the below screenshot:

Appearing when hovering feature

[stefaniamak]

FYI @skaldarnar @jdrueckert