Adds extension for configuring the release to the root project.
Configuration properties are loaded from gradle/shipkit.gradle file when the plugin is applied.
This mechanism assures that all properties are accessible during configuration phase.
If such file is not present, it will be created automatically with required properties and example values.
Important: it will add to the root project because this is where the configuration belong to!
Adds following behavior:
- Adds and preconfigures 'releasing' extension of type
ReleaseConfiguration
- Configures 'releasing.dryRun' setting based on 'releasing.dryRun' Gradle project property