feat: Make Kafka topic numPartitions and replicationFactor configurable

[velo]

Summary

• Adds engines.kafka.num-partitions (default 1) and engines.kafka.replication-factor (default 3) to default-package.json
• KafkaLogEngine reads them from the engine config and propagates them to both subscription/mutation topics
• The test-runner topics are restricted to 1 partition and 1 replication factor

[ferenc-csaky]

Logic itself LG, added 2 improvement suggestions.

[codecov]

Codecov Report

❌ Patch coverage is 7.14286% with 13 lines in your changes missing coverage. Please review.
✅ Project coverage is 13.52%. Comparing base (50acbc3) to head (a9ad6cf).
⚠️ Report is 3 commits behind head on main.
✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
...n/java/com/datasqrl/engine/log/kafka/NewTopic.java	14.28%	6 Missing ⚠️
...li/src/main/java/com/datasqrl/cli/DatasqrlRun.java	0.00%	5 Missing ⚠️
.../com/datasqrl/engine/log/kafka/KafkaLogEngine.java	0.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff            @@
##               main    #2086   +/-   ##
=========================================
  Coverage     13.52%   13.52%           
- Complexity      841      842    +1     
=========================================
  Files           605      605           
  Lines         17297    17304    +7     
  Branches       2091     2091           
=========================================
+ Hits           2340     2341    +1     
- Misses        14741    14747    +6     
  Partials        216      216           

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