Rework example task layout

[allnes]

What changed

• Moved the old example task directories into a single tasks/example tree with threads and processes/t1..t3 sections.
• Added shared settings.json, info.json, common, data, and tree-structured report.md files for the example task.
• Updated CMake, tests, the performance parser, and scoreboard support for the new example meta-layout.
• Updated documentation for the new example structure and the info.json format without task_number.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 27.94%. Comparing base (3b1f08c) to head (902fafb).

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #786      +/-   ##
==========================================
+ Coverage   27.07%   27.94%   +0.87%     
==========================================
  Files          15       15              
  Lines         495      501       +6     
  Branches      185      189       +4     
==========================================
+ Hits          134      140       +6     
  Misses        351      351              
  Partials       10       10              

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