test: add tests for fee voting

[mvadari]

High Level Overview of Change

This PR adds more comprehensive tests for fee voting, specifically the Smart Escrow parts.

Context of Change

An important part of the flow that has yet to be tested

Downstream of #5746

Type of Change

• Tests (you added tests for code that already exists, or your new feature included in this PR)

API Impact

N/A

Test Plan

This PR is only tests, and it passes in CI.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 79.3%. Comparing base (51ee064) to head (49c5ea7).

Additional details and impacted files

@@               Coverage Diff                @@
##           ripple/se/fees   #5747     +/-   ##
================================================
- Coverage            79.3%   79.3%   -0.0%     
================================================
  Files                 825     825             
  Lines               74283   74283             
  Branches             8504    8507      +3     
================================================
- Hits                58923   58918      -5     
- Misses              15360   15365      +5     

see 5 files with indirect coverage changes

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