Publish Android Artifact

Currently there is no separate Android Artifact, and there is no "minSdk" and other Android related information in the JAR we publish. This work is in progress and targeted for a 6.x release in 2023.

Related Issues:
* https://github.com/dropbox/dropbox-sdk-java/issues/285 - Issue has now rolled up into this ticket. By publishing an Android Artifact, we will need to specify the `minSdk` which we are aiming to set to 21.