refactor: system transaction proto changes

[mustafauzunn]

Description:

The idea is to clean the design of event transactions. Initially, we will support both repeated EventTransaction event_transaction and repeated bytes transaction in GossipEvent proto.

1. Inside TransactionBody add a new proto type - StateSignatureTransactionBody
2. Adapt GossipEvent proto to have repeated bytes transaction

Related issue(s):

Fixes #16675

Notes for reviewer:

Checklist

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

[codecov]

Codecov Report

Attention: Patch coverage is 66.66667% with 1 line in your changes missing coverage. Please review.

Project coverage is 63.65%. Comparing base (917ea25) to head (6ba1b95).
Report is 3 commits behind head on develop.

Files with missing lines	Patch %	Lines
.../src/main/java/com/hedera/hapi/util/HapiUtils.java	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             develop   #16702   +/-   ##
==========================================
  Coverage      63.65%   63.65%           
- Complexity     20449    20453    +4     
==========================================
  Files           2538     2538           
  Lines          94927    94929    +2     
  Branches        9919     9919           
==========================================
+ Hits           60425    60430    +5     
+ Misses         30887    30884    -3     
  Partials        3615     3615           

Files with missing lines	Coverage Δ
...m/hedera/node/config/data/ApiPermissionConfig.java	100.00% <100.00%> (ø)
...java/com/swirlds/platform/event/PlatformEvent.java	83.18% <100.00%> (ø)
.../src/main/java/com/hedera/hapi/util/HapiUtils.java	60.55% <0.00%> (-0.34%)	⬇️

... and 13 files with indirect coverage changes

[codacy-production]

Coverage summary from Codacy

See diff coverage on Codacy

Coverage variation	Diff coverage
✅ +0.00% (target: -1.00%)	✅ 66.67%

Coverage variation details

	Coverable lines	Covered lines	Coverage
Common ancestor commit (917ea25)	97692	63850	65.36%
Head commit (6ba1b95)	97694 (+2)	63855 (+5)	65.36% (+0.00%)

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 (#16702)	3	2	66.67%

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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[jsync-swirlds]

Just some suggested adjustments to clarify the intent and purpose for these changed data structures.

[anthony-swirldslabs]

platform-sdk/swirlds-platform-core/src/main/java/com/swirlds/platform/event/PlatformEvent.java

looks good to me.

[netopyr]

LGTM - thanks @mustafauzunn

[iwsimon]

LGTM.