[fatihguzeldev]

small immutable buffers throw in swap16(), swap32() and swap64().
larger buffers use native code, where the immutable check is missing.

add that check and let javascript throw the error when the native call
returns false. prepare the backing buffer before entering native code
to avoid allocation inside fast api callbacks.

refs: #66346

[codecov]

Codecov Report

❌ Patch coverage is 77.94118% with 15 lines in your changes missing coverage. Please review.
✅ Project coverage is 90.72%. Comparing base (6c8a697) to head (98b5d6a).
⚠️ Report is 3 commits behind head on main.

Files with missing lines	Patch %	Lines
src/node_buffer.cc	62.50%	0 Missing and 15 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #67392      +/-   ##
==========================================
- Coverage   90.73%   90.72%   -0.01%     
==========================================
  Files         798      798              
  Lines      280076   280127      +51     
  Branches    53880    53901      +21     
==========================================
+ Hits       254123   254150      +27     
- Misses      16259    16273      +14     
- Partials     9694     9704      +10     

Files with missing lines	Coverage Δ
lib/buffer.js	99.68% <100.00%> (+<0.01%)	⬆️
src/node_buffer.cc	75.00% <62.50%> (+0.13%)	⬆️

... and 32 files with indirect coverage changes

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