feat(code/starknet): Add mempool load generator to the Starknet test app

[oakenknight]

Closes: #801

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PR author checklist

For all contributors

• Reference GitHub issue
• Ensure PR title follows the conventional commits spec

For external contributors

• Maintainers of Malachite are allowed to push changes to the branch

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 80.81%. Comparing base (99124f5) to head (59994d3).
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #821      +/-   ##
==========================================
- Coverage   81.69%   80.81%   -0.88%     
==========================================
  Files         182      183       +1     
  Lines       16266    16394     +128     
==========================================
- Hits        13287    13248      -39     
- Misses       2979     3146     +167     

Flag	Coverage Δ
integration	80.60% <ø> (-0.92%)	⬇️
mbt	8.43% <ø> (-0.08%)	⬇️

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Components	Coverage Δ
core	∅ <ø> (∅)
engine	∅ <ø> (∅)
app	∅ <ø> (∅)
starknet	∅ <ø> (∅)