Avoid implicit property lookup in parent projects

Gradle 9.6 deprecated the implicit lookup of properties in parent
projects, which currently causes the build to emit deprecation
warnings and will become an error in Gradle 10.

The settings script for the gradle/plugins build sets properties
from the root gradle.properties file only on its root project. The
cycle-detection-plugin subproject then resolves javaFormatVersion
and checkstyleToolVersion by walking up to its parent, which
triggers the deprecation.

This commit uses GradleLifecycle#beforeProject rather than
Gradle#rootProject so that the properties are defined directly on
every project in the build. As an isolated action, it also avoids
carrying the settings script into each project's configuration,
which keeps the build friendlier to the configuration cache.

It also enables the NO_IMPLICIT_LOOKUP_IN_PARENT_PROJECTS feature
preview so that any reintroduction of the deprecated behavior fails
the build rather than only emitting a warning.

Signed-off-by: Hyunwoo Jung <hyunwoojung@kakao.com>

See gh-51625

gradle/plugins/settings.gradle

@@ -20,10 +20,12 @@ pluginManagement {
 		def properties = new Properties()
 		properties.load(it)
 		properties.forEach(settings.ext::set)
-		gradle.rootProject {
+		gradle.lifecycle.beforeProject {
 			properties.forEach(project.ext::set)
 		}
 	}
 }
 
+enableFeaturePreview("NO_IMPLICIT_LOOKUP_IN_PARENT_PROJECTS")
+
 include 'cycle-detection-plugin'

settings.gradle

@@ -45,6 +45,7 @@ plugins {
 rootProject.name="spring-boot-build"
 
 enableFeaturePreview("STABLE_CONFIGURATION_CACHE")
+enableFeaturePreview("NO_IMPLICIT_LOOKUP_IN_PARENT_PROJECTS")
 
 settings.gradle.projectsLoaded {
 	develocity {