Tutorial script ShowUIHighlight does not work consistently

[luxaritas]

ShowUIHighlight only works with some UI elements

This appears to be because of the following: https://github.com/eternagame/EternaJS/blob/dev/src/eterna/rscript/ROPHighlight.ts#L168 A reference to the UI element is requested with the fallback of the entire mode, and only in that fallback case is the highlight shown. Instead, we should always add the highlight to the top of the mode, and then get the world position of the thing being highlighted