[CHANGE] Randomized fill-in dynamic substitutions using Node

[D. Brian Walton]

A change was made behind the scenes in how the generated dynamic substitutions file for fill-in-the-blank problems with randomized elements are created. Previously, playwright used a headless browser and locally-hosted stand-alone html files for each problem. A new method was introduced that only loads the setup portion of the randomized problems using Node.js.

There is no change to the front-end.

This new method removes eliminates the need to open a temporary local html server, removes delays and timeouts relating to loading the html, and allows the creation of a simplified and better-formatted XML file containing the substitutions. [Note: This means the format of the dynamic-substitutions file—but not the actual substitutions—will change for projects previously generated.]

Requirements:

* Node is installed with minimum version v22.10

* A compatible version of npm is installed

The CLI will automatically verify requirements prior to generating the substitutions. Calling pretext/pretext directly with `-c dynamic` expects that `npm install` was previously run inside pretext/scripts/dynsub/.