buffer: fix end parameter bugs in indexOf/lastIndexOf

[ronag]

• Fix FastIndexOfNumber parameter order mismatch (end_i64 and is_forward were swapped vs the JS call site and slow path)
• Clamp negative end values to 0 to prevent size_t overflow in IndexOfString, IndexOfBuffer, and IndexOfNumberImpl
• Clamp empty needle result to search_end

Fixes: #62873

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 89.62%. Comparing base (4563cb3) to head (7d46b35).
⚠️ Report is 84 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #62711      +/-   ##
==========================================
+ Coverage   88.93%   89.62%   +0.69%     
==========================================
  Files         699      706       +7     
  Lines      216379   219169    +2790     
  Branches    41281    41994     +713     
==========================================
+ Hits       192434   196438    +4004     
+ Misses      15976    14619    -1357     
- Partials     7969     8112     +143     

Files with missing lines	Coverage Δ
src/node_buffer.cc	68.72% <100.00%> (+0.69%)	⬆️

... and 151 files with indirect coverage changes

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