refactor(kafka): change to byte collector

[ngjaying]

• Move batch implementation into Kafka sink itself
• Support template in batch
• Support different encode format besides json

[codecov]

Codecov Report

Attention: Patch coverage is 38.54167% with 59 lines in your changes missing coverage. Please review.

Project coverage is 71.11%. Comparing base (3e10b7f) to head (76e6cf2).
Report is 2 commits behind head on master.

Files with missing lines	Patch %	Lines
extensions/impl/kafka/sink.go	32.91%	52 Missing and 1 partial ⚠️
internal/testx/testUtil.go	55.56%	4 Missing ⚠️
internal/topo/planner/planner_sink.go	75.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #3545      +/-   ##
==========================================
- Coverage   71.19%   71.11%   -0.08%     
==========================================
  Files         417      417              
  Lines       48088    48138      +50     
==========================================
- Hits        34236    34232       -4     
- Misses      11182    11230      +48     
- Partials     2670     2676       +6     

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