[CdapIO] Complete examples for CDAP ServiceNow plugins

[Amar3tto]

Resolves #24961

Added examples for the following CDAP ServiceNow plugins:

• Batch Source

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[codecov]

Codecov Report

Merging #24590 (1a9d8a0) into master (f1fcf0a) will increase coverage by 0.00%.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master   #24590   +/-   ##
=======================================
  Coverage   73.35%   73.35%           
=======================================
  Files         719      719           
  Lines       97137    97137           
=======================================
+ Hits        71252    71253    +1     
+ Misses      24537    24536    -1     
  Partials     1348     1348           

Flag	Coverage Δ
python	82.98% <ø> (+<0.01%)	⬆️

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Impacted Files	Coverage Δ
.../python/apache_beam/transforms/periodicsequence.py	97.01% <0.00%> (-1.50%)	⬇️
...hon/apache_beam/runners/worker/bundle_processor.py	93.54% <0.00%> (-0.13%)	⬇️
...ks/python/apache_beam/runners/worker/sdk_worker.py	89.24% <0.00%> (+0.16%)	⬆️
sdks/python/apache_beam/runners/direct/executor.py	97.01% <0.00%> (+0.54%)	⬆️

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[Amar3tto]

Run Java_Kafka_IO_Direct PreCommit

[elizaveta-lomteva]

R: @johnjcasey

We divided our CDAP examples PR by example (service). This is the first one ready for review.
Could you please take the time to review it?

Thanks in advance!

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