[NTG-context] Containerized ConTeXt

[Thangalin]

Hi again,

I've added the start of a podman container for invoking ConTeXt that
may be of interest:

https://github.com/DaveJarvis/keenwrite/tree/main/container

The Containerfile sets up ConTeXt to work with my themes:

https://github.com/DaveJarvis/keenwrite-themes

The manage.sh shell script is a wrapper around the podman command to
help build, save, and load the container, as well as connect and run
commands. It's a work-in-progress.

My goal is to simplify the setup and configuration of ConTeXt as well
as make the instructions "cross platform" owing to containerization.
>From there, I want to call out to the container from KeenWrite to
typeset PDF documents using one of the themes. Further, I'd like to
have KeenWrite download and install ConTeXt automatically using
podman. I believe this will make it easier for people to generate
high-quality PDFs from (R) Markdown documents because they'd only have
to download KeenWrite, then ask KeenWrite to download/configure
ConTeXt automatically, in a cross-platform fashion.

Thoughts? Suggestions for improvement?