Switch build system to using poetry

[bobmoretti]

Switch Python build system to use poetry instead of virtualenv/shell

I really hate a lot of things about virtualenv. Seems that the "poetry" project for Python is the least bad of all the alternatives.

This also (mostly) obviates the need for shell scripts. Unfortunately I had a hell of a time getting the github actions runner instances to run shell commands inside Python scripts, so I gave up on doing that and just duplicated some of the functionality inside of the action yaml.

I also somehow ended up updating a bunch of frontend stuff, which led me down a chain of fixing a bunch of eslint warnings and removing all explicit uses of any from the code. It's more type safe now.

Before we could close this PR I would need to update the developer docs.

[bobmoretti]

Actually, I'm not sure if there are any developer docs. So I should probably write some.

[adamdoda]

We used to have something but I guess I've removed it.

[bobmoretti]

All tests passing, updated documentation, had to do something slightly awkward with the pydcs data files and pyinstaller, but I should be able to make a change upstream in pydcs to obviate that.