Extract reusable Google Health code into google-health-library

[this-Aditya]

This PR adds the reusable parts of the Google Health integration out of PushEndpoint and into a new google-health-library subproject, so other projects depend on the same building blocks instead of duplicating them.

Moved into the library: the JSON to Avro converters, the user/repository abstractions, the data-point models, the Avro builder helpers, and the shared exceptions.

[mpgxvii]

@this-Aditya Nice! So PushEndpoint will just rely on this as well? Also, should we add snapshot publishing so we can release snapshots for testing?

[this-Aditya]

Nice point, I've created a PR which will use radar-publishing from radar commons gradle which already handles this nicely

[mpgxvii]

Nice point, I've created a PR which will use radar-publishing from radar commons gradle which already handles this nicely

Great thank you!