Add interactive demo with binder

[bollwyvl]

Proposed change

Add a development-oriented configuration for binder which can be used for PR review as well as a demo.

References

• from Adopt hatchling, plugins for python package build #371 (comment)

Alternative options

Do nothing.

Who would use this feature?

Reviewers of PRs, etc.

This would also be a basically single-command way to get a full development environment that works on proprietary systems like Apple Silicon and Windows.

Suggest a solution

Add a binder configuration which fully encapsulates the development environment:

• .binder/apt.txt
  • include X11 dependencies needed to run firefox
• .binder/environment.yml
  • include all python packages
  • include as many contrib packages as possible
  • include a reasonably pinned version of nodejs, python, firefox, geckodriver, make, etc.
  • include nbgitpuller
    • though i don't think one can actually use a downstream config, due to how loading works
    • consider making it lazier in the future, a la kernelspecs, etc.
• .binder/postBuild
  • fully execute the dev build chain
    • build the js packages
    • build the python packages
    • build the docs
    • run the full test suite
  • don't block for anything except failing to build/install the packages
• README.md
  • add link to binder
• CONTRIBUTING.md
  • add note about keeping binder config up-to-date w/r/t pyproject.toml, etc.
• .github/workflows/binder.yml
  • add the binder PR link generator workflow