sea: add allowDynamicImportFromFileSystem config option

[thisalihassan]

Adds an explicit allowDynamicImportFromFileSystem config option for SEA. When set to true, import() from the injected main script can load modules from the file system. Default remains sealed (built-ins only), matching the current behavior.

This enables the common SEA pattern where a small bootstrap hands off to a user entrypoint on disk via dynamic import.
Refs: #62726

[nodejs-github-bot]

Review requested:

• @nodejs/loaders
• @nodejs/single-executable

[codecov]

Codecov Report

❌ Patch coverage is 97.43590% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 89.68%. Comparing base (978a8c4) to head (9d3200d).
⚠️ Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
src/node_sea.cc	95.23%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #62771      +/-   ##
==========================================
- Coverage   89.69%   89.68%   -0.01%     
==========================================
  Files         706      706              
  Lines      218222   218258      +36     
  Branches    41766    41768       +2     
==========================================
+ Hits       195726   195749      +23     
- Misses      14419    14425       +6     
- Partials     8077     8084       +7     

Files with missing lines	Coverage Δ
lib/internal/modules/esm/utils.js	99.51% <100.00%> (+0.01%)	⬆️
src/node_sea.h	100.00% <ø> (ø)
src/node_sea.cc	89.71% <95.23%> (+0.18%)	⬆️

... and 26 files with indirect coverage changes

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[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/72764/

[thisalihassan]

@joyeecheung rebased! can we re-run CI please?