chore: remove unused packages

[rix0rrr]

We moved cdk-build-tools and yarn-cling over from the old repo, but they are not really used here.

Just bockfs was being used as a testing tool -- move that into the aws-cdk package using it as a test helper.

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[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 84.94%. Comparing base (a1fbefe) to head (1ad5463).

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #240      +/-   ##
==========================================
+ Coverage   84.86%   84.94%   +0.07%     
==========================================
  Files         208      206       -2     
  Lines       35711    35215     -496     
  Branches     4626     4545      -81     
==========================================
- Hits        30306    29912     -394     
+ Misses       5258     5151     -107     
- Partials      147      152       +5     

Flag	Coverage Δ
suite.unit	84.94% <ø> (+0.07%)	⬆️

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