Support Gradle Isolated Projects feature in secrets-gradle-plugin. Currently using this plugin with -Dorg.gradle.unsafe.isolated-projects=true fails due to project.rootProject.loadPropertiesFile(it) as it reaches out to a the root project and that is not safe when all projects are configured at the same time.
Given the only reason rootProject is used is to get the root project directory, it should be easy to move to using Project.getRootDir that is Isolated Projects safe.