refactor!: split `r/demo/boards`

[harry-hov]

BREAKING CHANGE!

Found another p which imports r. It should not happen.

This PR splits r/demo/boards into r/demo/boards and p/demo/boards. Now p/demo/groups imports p/demo/boards instead of r/demo/boards

Related: #1393

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 48.44%. Comparing base (88b9aa3) to head (42c2a5e).

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #1989   +/-   ##
=======================================
  Coverage   48.44%   48.44%           
=======================================
  Files         409      409           
  Lines       61967    61967           
=======================================
  Hits        30019    30019           
  Misses      29448    29448           
  Partials     2500     2500           

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