Add Binder support

[blink1073]

Summary

• Adds binder/ configuration with environment.yml and postBuild to support launching the repo on Binder
• Adds examples/MetaKernel Python Demo.ipynb demonstrating available magics
• Fixes a bug in %set magic where non-string values (e.g. integers) caused an AttributeError in do_execute_direct
• Updates the README with a Binder launch badge opening directly to the demo notebook in classic notebook interface

Test plan

• Click the Binder badge in the README and verify the demo notebook opens in classic notebook
• Run through the demo notebook cells to verify magics work correctly
• Run just test to confirm the %set bug fix is covered by the updated test_set_get_magic.py tests

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.95%. Comparing base (a00ba16) to head (1ed7664).

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #361   +/-   ##
=======================================
  Coverage   90.95%   90.95%           
=======================================
  Files          51       51           
  Lines        2874     2874           
  Branches      402      402           
=======================================
  Hits         2614     2614           
  Misses        181      181           
  Partials       79       79           

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