feat: add callback support in send method of event producer

[GurtejSohi]

Description

The send method in our KafkaEventProducer library calls the send method of Apache's KafkaProducer which returns a Future but our library ignores it. As the documentation says, "The send is asynchronous and this method will return immediately once the record has been stored in the buffer of records waiting to be sent." Calling send() does NOT mean the record is already written to Kafka. If the client wants to check/ensure that the record was successfully written to Kafka, the client should check the Future returned by Apache KakaProducer's send method or provide a callback to the send method. But our library doesn't provide any of these capabilities. So, there is no way for the client of our library to know if there were any errors while writing to Kafka.

To address this shortcoming, I've added send method which accepts a callback.

[github-actions]

Test Results

0 tests  ±0   0 ✅ ±0   0s ⏱️ ±0s
0 suites ±0   0 💤 ±0 
0 files   ±0   0 ❌ ±0 

Results for commit 020cd6f. ± Comparison against base commit 76a8dfa.

[codecov]

Codecov Report

❌ Patch coverage is 0% with 32 lines in your changes missing coverage. Please review.
✅ Project coverage is 0.00%. Comparing base (76a8dfa) to head (020cd6f).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
...race/core/eventstore/kafka/KafkaEventProducer.java	0.00%	21 Missing ⚠️
...ava/org/hypertrace/core/eventstore/SendResult.java	0.00%	11 Missing ⚠️

Additional details and impacted files

@@          Coverage Diff          @@
##            main     #16   +/-   ##
=====================================
  Coverage   0.00%   0.00%           
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  Files          9      10    +1     
  Lines        187     219   +32     
  Branches       9      11    +2     
=====================================
- Misses       187     219   +32     

Flag	Coverage Δ
unit	0.00% <0.00%> (ø)

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