[Finishes #75389176] Allow ??? in blocks while level building, treat as ...

...wildcards for matching

Allows level builders to use ??? in number fields.  When they do so, we will allow any value for block matching purposes.  If the block is missing and we want to display it for feedback, we will display the block with ???.
Out of curiosity, what's an example of a non-element that would come in? Only raw text nodes?