ffi: reject non-boolean copy arguments

[christianaurichzm]

ffi.toBuffer() and ffi.toArrayBuffer() document copy as a boolean, but currently coerce other values through BooleanValue().

This means falsy values such as null, 0, and '' select zero-copy mode instead of throwing:

const ffi = require('node:ffi');

const source = Buffer.from([1]);
const ptr = ffi.getRawPointer(source);

const view = ffi.toBuffer(ptr, 1, null);
view[0] = 42;

console.log(source[0]); // 42

Truthy non-booleans such as 'false' and 1 are accepted as well and select the copy path.

Reject non-boolean values with ERR_INVALID_ARG_TYPE. Omitting copy or passing undefined still defaults to copying, and true and false keep their existing behavior.

node:ffi is experimental and the documented type for copy is {boolean}.

Testing:

• tools/test.py parallel sequential ffi
• make lint
• make lint-cpp
• make format-cpp

[nodejs-github-bot]

Review requested:

• @nodejs/ffi

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.27%. Comparing base (c0ed28f) to head (abc3d45).
⚠️ Report is 89 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #66219      +/-   ##
==========================================
- Coverage   90.29%   90.27%   -0.02%     
==========================================
  Files         790      790              
  Lines      272883   272886       +3     
  Branches    52118    52105      -13     
==========================================
- Hits       246387   246350      -37     
- Misses      16943    16996      +53     
+ Partials     9553     9540      -13     

Files with missing lines	Coverage Δ
src/ffi/data.cc	78.43% <100.00%> (+0.14%)	⬆️

... and 23 files with indirect coverage changes

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[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/77894/

[panva]

Landed in 63a6ea2