feat: improve chunkMessages function in terms of cpu/mem

[Abdulsametileri]

When I run batch consumer, kafka-konsumer runs the chunkMessages function for every incoming batch of messages (consume function in batch_consumer.go).

I wrote more effective chunkMessages.

Here the benchmark results (I used benchstat, random test data etc)

Execution Time (sec/op)

Original Function: 96.90µs per operation
Optimized Function: 48.35µs per operation
Improvement: %50 faster

Memory Usage (B/op)

Original Function: 299.1KiB per operation
Optimized Function: 170.1KiB per operation
Improvement: Approximately 43% reduction in memory usage

Number of Allocations (allocs/op)

Original Function: 809 allocations per operation
Optimized Function: 102 allocations per operation
Improvement: Approximately 87% reduction in allocations

You can also find benchmark tests, and run (make run-benchmarks)