[WIP] Migrate ContextifyContext to cppgc

[joyeecheung]

This simplifies the memory management of ContextifyContext, making all the references known to V8's GC.

Depends on #56534

[codecov]

Codecov Report

Attention: Patch coverage is 76.47059% with 8 lines in your changes missing coverage. Please review.

Project coverage is 89.17%. Comparing base (7c3aa9f) to head (547062e).
Report is 10 commits behind head on main.

Files with missing lines	Patch %	Lines
src/node_contextify.cc	65.00%	7 Missing ⚠️
src/node_contextify.h	50.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #56522      +/-   ##
==========================================
+ Coverage   89.12%   89.17%   +0.04%     
==========================================
  Files         662      662              
  Lines      191556   191589      +33     
  Branches    36860    36863       +3     
==========================================
+ Hits       170732   170846     +114     
+ Misses      13690    13601      -89     
- Partials     7134     7142       +8     

Files with missing lines	Coverage Δ
src/api/embed_helpers.cc	74.75% <100.00%> (+0.12%)	⬆️
src/env.cc	85.63% <100.00%> (-0.04%)	⬇️
src/env.h	98.14% <ø> (ø)
src/node_main_instance.cc	90.27% <100.00%> (ø)
src/node_worker.cc	83.46% <100.00%> (-0.49%)	⬇️
src/node_contextify.h	85.71% <50.00%> (+12.38%)	⬆️
src/node_contextify.cc	81.48% <65.00%> (+0.11%)	⬆️

... and 56 files with indirect coverage changes

[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/64425/