process: throw on execve(2) failure instead of aborting

[bengl]

When the underlying execve(2) system call fails, process.execve() previously printed an error to stderr and called ABORT(), preventing JS code from detecting or recovering from common failures such as a missing binary. Throw an ErrnoException instead, carrying the usual code, errno, syscall, and path properties.

To leave the process in a clean state when execve(2) fails, no longer run native AtExit callbacks before the call (their in-memory effects are discarded on success anyway), and snapshot and restore the FD_CLOEXEC flags on stdio so a failed call has no observable side effects. Rename and update test-process-execve-abort.js accordingly and document the new behaviour.

[codecov]

Codecov Report

❌ Patch coverage is 52.63158% with 9 lines in your changes missing coverage. Please review.
✅ Project coverage is 89.62%. Comparing base (c29a34c) to head (55e4b8f).
⚠️ Report is 6 commits behind head on main.

Files with missing lines	Patch %	Lines
src/node_process_methods.cc	52.63%	7 Missing and 2 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #62878      +/-   ##
==========================================
- Coverage   89.62%   89.62%   -0.01%     
==========================================
  Files         706      706              
  Lines      219165   219170       +5     
  Branches    41989    42000      +11     
==========================================
+ Hits       196435   196439       +4     
+ Misses      14621    14615       -6     
- Partials     8109     8116       +7     

Files with missing lines	Coverage Δ
src/node_process_methods.cc	88.52% <52.63%> (+0.34%)	⬆️

... and 30 files with indirect coverage changes

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[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/72851/

[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/72852/

[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/72853/

[bengl]

@jasnell adding you as a reviewer since you had the initial suggestion to just abort when execve fails. The approach I took here is a bit of a departure, since RunAtExit is no longer called. I think this approach makes sense because the process isn't so much "exiting" as being replaced entirely, as is the nature of execve. The benefit of being able to recover from ENOENT, for example, seems worth it.