[Java] Add Automatic-Module-Name to Manifest file

[danepitkin]

This change explicitly defines the module name for flatbuffers for Java 9+. Without this configuration, the module name is auto-generated based on the filename flatbuffers-java.

This is the current warning during compile time for downstream projects:

Warning:  **********************************************************************************************************************************************************************
Warning:  * Required filename-based automodules detected: [flatbuffers-java-24.3.25.jar]. Please don't publish this project to a public artifact repository! *
Warning:  **********************************************************************************************************************************************************************

Fixes: #8348

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[danepitkin]

This Flatbuffers PR will benefit the Java community. It prevents Java module dependency problems when multiple downstream libraries want to use Flatbuffers. Apache Arrow is one such project that utilizes Java Flatbuffers and supports JPMS. I found a blog post that provides a detailed description of the problem: https://blog.joda.org/2017/05/java-se-9-jpms-automatic-modules.html cc @dbaileychess

[danepitkin]

Closing in favor of #8367