PUBLISH: 18th March 2022

ENH: Use sphinx-exercise for Styled Exercises and Solutions (#176)

* [functions]Migrating exercise to use sphinx-exercise

* add sphinx-exercise

* pull out code-cell until supported

* TST: new gated directives

* Enable dropdown via sphinx-togglebutton

* TST: see if sphinx-togglebutton works in sphinx_book_theme

* Restore quantecon-book-theme

* Empty commit to trigger rebuild

* Update all solutions to be hidden by default

* Update for sphinx-exercise

* Migrate to sphinx-exercise

* migrate to sphinx-exercise

* fix numpy syntax issue

* fix broken label

* Enable dropdown toggle for solutions

* Enable dropdown toggle for solutions

* move to use pypi sphinx-exercise==0.4.1

* upgrade sphinx-tojupyter==0.2.1

Co-authored-by: Shu <shu.hu@anu.edu.au>