Replace the Hiero Conventions Gradle Plugin with local gradle configuration

The Hiero Conventions plugin establishes a specific style and structure that may not be a good fit for all situations.

As part of publishing this project for broad use we wish to remove that plugin and replace it with local gradle configuration for greater locality of build and greater flexibility.

An alternative approach might be to split the Hiero Conventions plugin into "useful tooling" and "project preferences" then apply the tooling plugin without the project preferences.