Implement UDP transport for air-gap sink

[Caideyipi]

Summary

• Add tcp/udp transport option and UDP packet size validation for air-gap connector/sink.
• Send UDP air-gap datagrams with the existing envelope/ACK flow and slice oversized requests.
• Make the receiver listen on UDP on the air-gap port and keep per UDP client receiver/session state.

Tests

• mvn -DskipTests spotless:apply -pl iotdb-core/node-commons,iotdb-core/datanode
• mvn -pl iotdb-core/node-commons -DskipTests compile
• git diff --check
• mvn -pl iotdb-core/datanode -Dtest=IoTDBDataRegionAirGapSinkTest,IoTDBAirGapReceiverTest test (fails during existing datanode compilation: missing parser/generated/calc/consensus symbols such as AlterTopicContext, ComparatorChain, PERCENTILE, and IStateMachine.loadSnapshot return mismatch)

[sonarqubecloud]

Quality Gate passed

Issues
3 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[codecov]

Codecov Report

❌ Patch coverage is 56.22318% with 102 lines in your changes missing coverage. Please review.
✅ Project coverage is 41.16%. Comparing base (8fad784) to head (50aa7a8).
⚠️ Report is 4 commits behind head on master.

Files with missing lines	Patch %	Lines
...iver/protocol/airgap/IoTDBAirGapReceiverAgent.java	7.40%	50 Missing ⚠️
.../receiver/protocol/airgap/IoTDBAirGapReceiver.java	39.21%	31 Missing ⚠️
...db/commons/pipe/sink/protocol/IoTDBAirGapSink.java	84.61%	18 Missing ⚠️
...er/protocol/thrift/IoTDBDataNodeReceiverAgent.java	62.50%	3 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##             master   #17954      +/-   ##
============================================
+ Coverage     41.15%   41.16%   +0.01%     
  Complexity      318      318              
============================================
  Files          5258     5258              
  Lines        365613   365819     +206     
  Branches      47282    47307      +25     
============================================
+ Hits         150460   150603     +143     
- Misses       215153   215216      +63     

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