Remove make and related compromises

[dalito]

Motivation:

• handling escaping correctly is difficult, see e.g.
  • Fix make vars and improve docs gen linkml/linkml-project-cookiecutter#123
  • .env.public approach to Makefile variables: quotes are literal in GNU Make linkml/linkml-project-cookiecutter#106)
• only a simple command runner is needed but make is primarily designed for building files with complex dependencies. The complexity of make may lead to issues like
  • Spurious error when running make setup for the first time linkml/linkml-project-cookiecutter#124
• make is not readily available on Windows

Instead of make this template uses just which is a tool that feels similar to make but is designed explicitly for the purpose of running commands. Interesting reads:

• just-stop-using-makefile - on when to pick just and when make
• I've tried the "just" task runner. Is it worth it?