[query-engine] Reduce complexity in mutable value selection operations in RecordSet engine

[CodeBlanch]

Changes

• Switch selection helper methods from Result<Option<ResolvedValueMut<'b, 'c>>, ExpressionError> to just Option<ResolvedValueMut<'b, 'c>> because they weren't returning errors

[codecov]

Codecov Report

❌ Patch coverage is 70.58824% with 5 lines in your changes missing coverage. Please review.
✅ Project coverage is 83.52%. Comparing base (99113cf) to head (2604793).
⚠️ Report is 4 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1546      +/-   ##
==========================================
- Coverage   83.55%   83.52%   -0.04%     
==========================================
  Files         428      428              
  Lines      119720   119716       -4     
==========================================
- Hits       100038    99995      -43     
- Misses      19148    19187      +39     
  Partials      534      534              

Components	Coverage Δ
otap-dataflow	84.69% <ø> (-0.07%)	⬇️
query_abstraction	80.61% <ø> (ø)
query_engine	90.31% <70.58%> (+<0.01%)	⬆️
syslog_cef_receivers	∅ <ø> (∅)
otel-arrow-go	53.50% <ø> (ø)

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