buffer: fix negative index for large buffers

[Dansatch]

Fixes #66294.

Buffer.prototype.indexOf() returned a negative position when a match occurred beyond 2 GiB because the result was converted to a signed 32-bit integer.

This change returns the position as a JavaScript number and adds regression tests for number, Buffer, and string searches.

[github-actions]

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[codecov]

Codecov Report

❌ Patch coverage is 85.71429% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 90.36%. Comparing base (c0681e5) to head (8861a47).
⚠️ Report is 21 commits behind head on main.

Files with missing lines	Patch %	Lines
src/node_buffer.cc	85.71%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #66325      +/-   ##
==========================================
- Coverage   90.37%   90.36%   -0.02%     
==========================================
  Files         790      792       +2     
  Lines      274514   275324     +810     
  Branches    52572    52768     +196     
==========================================
+ Hits       248102   248785     +683     
- Misses      16889    16964      +75     
- Partials     9523     9575      +52     

Files with missing lines	Coverage Δ
src/node_buffer.cc	70.41% <85.71%> (ø)

... and 55 files with indirect coverage changes

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[panva]

Use int64_t instead of double for the casts and return types. The result is an integer offset or -1, and int64_t fixes the overflow while still exposing a JavaScript Number.

double also disables this Fast API signature on PPC64 and s390x. int64_t keeps it eligible.

[panva]

Suggested change

	assert.strictEqual(buffer.indexOf(0x0a, match), match);
	assert.strictEqual(buffer.indexOf(Buffer.from([0x0a]), match), match);
	assert.strictEqual(buffer.indexOf('\n', match), match);
	assert.strictEqual(buffer.indexOf(0x0a, -1), match);
	assert.strictEqual(buffer.indexOf(Buffer.from([0x0a]), -1), match);
	assert.strictEqual(buffer.indexOf('\n', -1), match);
	assert.strictEqual(buffer.lastIndexOf(0x0a, -1), match);
	assert.strictEqual(buffer.lastIndexOf(Buffer.from([0x0a]), -1), match);
	assert.strictEqual(buffer.lastIndexOf('\n', -1), match);

[Dansatch]

I appreciate your review.
I’ve switched the return types and casts to int64_t, moved the test to test/pummel and added the suggested indexOf() and lastIndexOf() assertions.