Publish the SDK under the Hiero namespace

As previously announced in September 2024, Hedera projects have migrated to Hiero under Linux Foundation Decentralized Trust. As part of this transition, the Java SDK needs to be published under the Hiero namespace.

[Single-Step Cutover
](https://hedera.com/blog/namespace-transition-announcement-hedera-projects-moving-to-hiero)This involves a complete switch from the old namespace to the new one in a single, clearly defined release. After this release, new SDK updates will only be available under the new namespace. Older versions will remain accessible under the original hashgraph namespace but will no longer receive updates or new features.

- The Java SDK will transition to the new namespace starting from version 2.80.0 (approximately in 9 months from the [announcement](https://hedera.com/blog/namespace-transition-announcement-hedera-projects-moving-to-hiero) date).
- This change involves updating your build tools (e.g., Maven or Gradle configurations) to reflect the new groupId (org.hiero) and artifactId (hiero-sdk).

Will need to update the gradle build configuration.

- Update the packages to the new Hiero namespace
- Update the workflow to publish under the new namespace when releasing