When the GraalVM Native Image Gradle plugin is applied, configure bootJar to contain the output of collectReachabilityMetadata

[philwebb]

Once we have an NBT release with graalvm/native-build-tools#322 in it we should provide some configuration to ensure reachability metadata is included in jars created by the user.

[philwebb]

This will supersede #32408 and allow override support