refactor: adapt StatsSigningTestingTool to work with Bytes wrapper for transactions

[IvanKavaldzhiev]

Description:
This PR updates StatsSigningTestingTool to work with the new Bytes format of system transactions.

Related issue(s):

Fixes #16871

Notes for reviewer:

Checklist

• Documented (Code comments, README, etc.)
• Tested (unit, integration, etc.)

[codecov]

Codecov Report

Attention: Patch coverage is 71.79487% with 11 lines in your changes missing coverage. Please review.

Project coverage is 67.95%. Comparing base (307b469) to head (3a1cead).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
...emo/stats/signing/StatsSigningTestingToolMain.java	60.00%	4 Missing ⚠️
...igning/StatsSigningTestingToolStateLifecycles.java	83.33%	3 Missing and 1 partial ⚠️
...swirlds/demo/stats/signing/SttTransactionPool.java	0.00%	2 Missing ⚠️
...m/swirlds/demo/stats/signing/TransactionCodec.java	66.66%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##               main   #17144      +/-   ##
============================================
+ Coverage     67.76%   67.95%   +0.18%     
- Complexity    22281    22344      +63     
============================================
  Files          2606     2606              
  Lines         96872    96901      +29     
  Branches      10094    10098       +4     
============================================
+ Hits          65643    65845     +202     
+ Misses        27483    27295     -188     
- Partials       3746     3761      +15     

Files with missing lines	Coverage Δ
...m/swirlds/demo/stats/signing/TransactionCodec.java	34.56% <66.66%> (+34.56%)	⬆️
...swirlds/demo/stats/signing/SttTransactionPool.java	1.53% <0.00%> (+1.53%)	⬆️
...emo/stats/signing/StatsSigningTestingToolMain.java	30.70% <60.00%> (+30.70%)	⬆️
...igning/StatsSigningTestingToolStateLifecycles.java	49.36% <83.33%> (+49.36%)	⬆️

... and 6 files with indirect coverage changes

[codacy-production]

Coverage summary from Codacy

See diff coverage on Codacy

Coverage variation	Diff coverage
✅ +0.20% (target: -1.00%)	✅ 76.92%

Coverage variation details

	Coverable lines	Covered lines	Coverage
Common ancestor commit (307b469)	96655	69237	71.63%
Head commit (3a1cead)	96684 (+29)	69454 (+217)	71.84% (+0.20%)

Coverage variation is the difference between the coverage for the head and common ancestor commits of the pull request branch: <coverage of head commit> - <coverage of common ancestor commit>

Diff coverage details

	Coverable lines	Covered lines	Diff coverage
Pull request (#17144)	39	30	76.92%

Diff coverage is the percentage of lines that are covered by tests out of the coverable lines that the pull request added or modified: <covered lines added or modified>/<coverable lines added or modified> * 100%

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_{Codacy stopped sending the deprecated coverage status on June 5th, 2024. Learn more}

[andrewb1269hg]

Reviewed file platform-sdk/platform-apps/tests/StatsSigningTestingTool/build.gradle.kts and approved.

[andrewb1269hg]

Review and approve file platform-sdk/platform-apps/tests/StatsSigningTestingTool/build.gradle.kts

[mishomihov00]

Review applies to platform-sdk/platform-apps/tests/StatsSigningTestingTool/build.gradle.kts