refactor: Factor out Transactor::trapTransaction

[Bronek]

High Level Overview of Change

A more convenient location to set a breakpoint when replaying transactions.

Context of Change

This is a follow-up to #5027 , suggested by @ximinez

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Refactor (non-breaking change that only restructures code)
• Performance (increase or change in throughput and/or latency)
• Tests (you added tests for code that already exists, or your new feature included in this PR)
• Documentation update
• Chore (no impact to binary, e.g. .gitignore, formatting, dropping support for older tooling)
• Release

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 74.8%. Comparing base (7d27b11) to head (43b9c6e).

Additional details and impacted files

@@            Coverage Diff            @@
##           develop   #5087     +/-   ##
=========================================
- Coverage     74.8%   74.8%   -0.0%     
=========================================
  Files          766     766             
  Lines        63002   63004      +2     
  Branches      8839    8839             
=========================================
- Hits         47144   47142      -2     
- Misses       15858   15862      +4     

Files	Coverage Δ
src/xrpld/app/tx/detail/Transactor.cpp	84.7% <100.0%> (+0.1%)	⬆️
src/xrpld/app/tx/detail/Transactor.h	100.0% <ø> (ø)

... and 3 files with indirect coverage changes