Split up enableFeaturePreviewQuietly internals to callable parts

[TWiStErRob]

workaround:

enableFeaturePreviewQuietly("STABLE_CONFIGURATION_CACHE", "Kotlin DSL property assignment")

[TWiStErRob]

Also remove receiver, so this is not necessary in cinema

buildscript {
	dependencyLocking {
		lockAllConfigurations()
		// To prevent "Kotlin DSL property assignment", don't use it here.
		lockFile.set(file("../../gradle/dependency-locks/plugins-settings.lockfile"))
	}
}