Enable the Gradle configuration cache

Set org.gradle.configuration-cache=true so Gradle can skip the configuration phase when nothing it depends on has changed. Deliberately not part of org.openrewrite.gradle.GradleBestPractices: enabling it surfaces configuration cache violations in build logic that have to be fixed by hand before the build will run, so this is the first half of a change whose second half a recipe cannot make. See the Gradle best practice.