Find a good Variable Inspector that AREPL can use

Right now, the variable inspector just prints the variable values in a very simple way. Other projects (such as VSCode) have standard Variable Inspectors that are considerably more powerful.

It'd be great to have some of those features. Even better if AREPL can get them by reusing someone else's code rather than having to write a new one. So, this is a thread for looking at existing ones, and leaning towards ease of integration rather than power & features.

Note: Keep an eye on license compatibility! We _may_ need code that's compatible with AREPL's MIT license.