ffi: remove permission checks from dlclose and dlsym

[trivikr]

Fixes: #66425

The docs describe ffi.dlclose(handle) and ffi.dlsym(handle, symbol) as equivalent to handle.close() and handle.getSymbol(symbol), but only the functions called checkFFIPermission(). After process.permission.drop('ffi'), ffi.dlclose(lib) threw ERR_ACCESS_DENIED while lib.close() succeeded.

Remove the checks so the functions defer to the handle. Permission is already checked when the DynamicLibrary is constructed, and dropping a permission does not revoke resources that are already open.

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Assisted-by: claude:opus-5.5

[nodejs-github-bot]

Review requested:

• @nodejs/ffi

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.37%. Comparing base (d7ea02d) to head (b83b2af).
⚠️ Report is 3 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main   #66426   +/-   ##
=======================================
  Coverage   90.37%   90.37%           
=======================================
  Files         792      792           
  Lines      275683   275681    -2     
  Branches    52854    52849    -5     
=======================================
- Hits       249147   249146    -1     
+ Misses      16947    16941    -6     
- Partials     9589     9594    +5     

Files with missing lines	Coverage Δ
lib/ffi.js	96.35% <ø> (-0.02%)	⬇️

... and 13 files with indirect coverage changes

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[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/78120/