Replace core state counter synchronization with device kernels and functors

[LSchwiebert]

This is a draft PR for discussion purposes. Any coding comments are welcome, of course. This shows the status of the current changes as a foundation for addressing the more challenging cases.

[github-actions]

Test summary

 6 045 files   9 782 suites   8m 21s ⏱️
 1 828 tests  1 818 ✅  10 💤 0 ❌
32 351 runs  32 164 ✅ 187 💤 0 ❌

Results for commit 99a4228.

♻️ This comment has been updated with latest results.

[codecov]

Codecov Report

❌ Patch coverage is 80.27523% with 43 lines in your changes missing coverage. Please review.
✅ Project coverage is 85.79%. Comparing base (cbcaa74) to head (99a4228).
⚠️ Report is 3 commits behind head on develop.

Files with missing lines	Patch %	Lines
src/accel/LocalOpticalGenOffload.cc	55.55%	6 Missing and 2 partials ⚠️
src/celeritas/optical/Runner.cc	56.25%	6 Missing and 1 partial ⚠️
.../celeritas/optical/gen/detail/GeneratorExecutor.hh	77.77%	5 Missing and 1 partial ⚠️
.../celeritas/optical/action/LocateVacanciesAction.cc	68.75%	5 Missing ⚠️
src/celeritas/global/Stepper.cc	75.00%	3 Missing ⚠️
src/celeritas/optical/gen/GeneratorBase.cc	57.14%	3 Missing ⚠️
src/celeritas/track/ExtendFromPrimariesAction.cc	70.00%	3 Missing ⚠️
src/celeritas/optical/gen/DirectGeneratorAction.cc	50.00%	1 Missing and 1 partial ⚠️
...leritas/optical/gen/detail/WlsGeneratorExecutor.hh	50.00%	1 Missing and 1 partial ⚠️
...ritas/optical/action/detail/TrackInitAlgorithms.hh	0.00%	1 Missing ⚠️
... and 3 more

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #2376      +/-   ##
===========================================
- Coverage    87.27%   85.79%   -1.48%     
===========================================
  Files         1393     1365      -28     
  Lines        44011    42459    -1552     
  Branches     13428    10937    -2491     
===========================================
- Hits         38409    36429    -1980     
- Misses        4365     4397      +32     
- Partials      1237     1633     +396     

Files with missing lines	Coverage Δ
src/accel/LocalOpticalGenOffload.hh	100.00% <ø> (+14.28%)	⬆️
src/celeritas/global/Stepper.hh	100.00% <ø> (ø)
src/celeritas/global/TrackExecutor.hh	100.00% <100.00%> (ø)
...rc/celeritas/global/detail/SetGeneratedExecutor.hh	100.00% <100.00%> (ø)
src/celeritas/optical/CoreState.hh	100.00% <ø> (ø)
src/celeritas/optical/Runner.hh	100.00% <ø> (ø)
src/celeritas/optical/TrackInitData.hh	90.00% <ø> (-0.91%)	⬇️
.../celeritas/optical/action/LocateVacanciesAction.hh	100.00% <ø> (ø)
...ritas/optical/action/detail/TrackInitAlgorithms.cc	100.00% <100.00%> (ø)
...ritas/optical/action/detail/UpdateAliveExecutor.hh	100.00% <100.00%> (ø)
... and 29 more

... and 729 files with indirect coverage changes

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