feat: Add Map batch

[RohanAshar]

Fixes numaproj/numaflow#1789
Fixes numaproj/numaflow#1846

[codecov]

Codecov Report

Attention: Patch coverage is 73.91304% with 48 lines in your changes missing coverage. Please review.

Please upload report for BASE (main@3c2ec6f). Learn more about missing BASE report.

Files	Patch %	Lines
...java/io/numaproj/numaflow/batchmapper/Service.java	74.35%	15 Missing and 5 partials ⚠️
.../java/io/numaproj/numaflow/batchmapper/Server.java	57.77%	16 Missing and 3 partials ⚠️
...java/io/numaproj/numaflow/batchmapper/Message.java	70.00%	3 Missing ⚠️
...maproj/numaflow/batchmapper/DatumIteratorImpl.java	87.50%	1 Missing and 1 partial ⚠️
...a/io/numaproj/numaflow/shared/GrpcServerUtils.java	50.00%	1 Missing and 1 partial ⚠️
...va/io/numaproj/numaflow/batchmapper/Constants.java	0.00%	1 Missing ⚠️
...a/io/numaproj/numaflow/batchmapper/GRPCConfig.java	80.00%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #132   +/-   ##
=======================================
  Coverage        ?   59.43%           
  Complexity      ?      361           
=======================================
  Files           ?      120           
  Lines           ?     2384           
  Branches        ?      169           
=======================================
  Hits            ?     1417           
  Misses          ?      837           
  Partials        ?      130           

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[KeranYang]

Partial Review. Thanks @RohanAshar for quickly pick this up and create the PR. 👍

[yhl25]

As discussed, let's use threads instead of Akka actors. Since we don't see much benefit in using actors over threads and also to be consistent with the current sink implementation.

[KeranYang]

@RohanAshar one more comment and this is probably an unknown unknown to you - we have a build-push workflow, which automatically builds the example image using the latest change and push it to quay.io. Most of our examples are built into an image and used by numaflow e2e tests, having the auto image update help us ensure the SDK changes are validated by numaflow e2e. As we are going to use the example in the PR for batch map java e2e test, we should add it to the workflow yaml file. https://github.com/numaproj/numaflow-java/blob/main/development.md#adding-a-new-example

[KeranYang]

LGTM. I am approving with one minor comment. Please monitor the build-push workflow and enable e2e test on numaflow repo. Thanks!

[KeranYang]

@RohanAshar I have manually created the repository https://quay.io/repository/numaio/numaflow-java/batch-map-example and granted the CI account permission to push the image. Should be good to monitor the build-push workflow after merging.