feat: change consumeFn and batchConsumeFn as pointer signature

[Abdulsametileri]

Users should modify the message, for example, adding a new header or removing the old one. To pass this modification to the exception topic, we need to pass the message as a pointer.

[codecov]

Codecov Report

Attention: 4 lines in your changes are missing coverage. Please review.

Comparison is base (326fc77) 31.19% compared to head (af8af57) 31.81%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #62      +/-   ##
==========================================
+ Coverage   31.19%   31.81%   +0.61%     
==========================================
  Files          19       19              
  Lines         609      613       +4     
==========================================
+ Hits          190      195       +5     
+ Misses        413      412       -1     
  Partials        6        6              

Files	Coverage Δ
consumer.go	36.84% <100.00%> (ø)
consumer_config.go	17.80% <ø> (ø)
batch_consumer.go	57.62% <66.66%> (ø)
consumer_base.go	14.92% <0.00%> (ø)
message.go	70.00% <81.81%> (+3.33%)	⬆️

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[Abdulsametileri]

We can also merge this mr with nonbatch error implementation. In that case, we are considering returning []error array, etc. @emreodabas we can discuss further