test,doc: cover and document multi-byte offset/size in randomFill

[kyungrae2002]

• Document that offset/size are in elements for a TypedArray and in
  bytes for an ArrayBuffer / DataView (default given per type)
• Fix randomFill() throwing for ArrayBuffer / DataView with an offset,
  where buf.length - offset becomes NaN
• Add regression tests for multi-byte offset/size and the offset case

[nodejs-github-bot]

Review requested:

• @nodejs/crypto

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.17%. Comparing base (ed63b19) to head (fe7d6b1).
⚠️ Report is 336 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #64834      +/-   ##
==========================================
- Coverage   92.01%   90.17%   -1.85%     
==========================================
  Files         381      746     +365     
  Lines      170167   242763   +72596     
  Branches    26075    45762   +19687     
==========================================
+ Hits       156585   218906   +62321     
- Misses      13291    15325    +2034     
- Partials      291     8532    +8241     

Files with missing lines	Coverage Δ
lib/internal/crypto/random.js	96.09% <100.00%> (ø)

... and 533 files with indirect coverage changes

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[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/75407/

[nodejs-github-bot]

Landed in 65a0265