This commit moves the configuration of a local Maven deployment
repository in a dedicated Gradle convention and applies it to all
sub-projects. This separates the publishing configuration for actual
project modules (that are meant to be published on Maven Central) from
the infrastructure sub-projects such as the documentation one.
This commit refactors the Gradle build with the following:
* use of the dependency management plugin
* import the Spring Boot BOM for dependency management
* add support for publishing artifacts
