fix: Move shaded jar into separate package

[EnricoMi]

Description

In #239, I had added a shaded version of the jar. However, that shares the pom.xml with the main jar, hence all dependencies are still referenced. The shaded pom has to be published under its own package name.

This publishes the shaded jar under dgraph4j-shaded.

Checklist

• Code compiles correctly and linting passes locally
• For all code changes, an entry added to the CHANGELOG.md file describing and linking to
  this PR
• Tests added for new functionality, or regression tests for bug fixes added as applicable
• For public APIs, new features, etc., PR on
  docs repo staged and linked here

Co-Authored-By: Claude noreply@anthropic.com

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