Deprecate KmModule.annotations because it is unused and always empty.

It used to store state of `-Xexperimental` Kotlin compilation flag,
but this feature was removed long ago.

#KT-59366 Fixed

libraries/kotlinx-metadata/jvm/src/kotlinx/metadata/jvm/KotlinModuleMetadata.kt

@@ -249,7 +249,10 @@ class KmModule : KmModuleVisitor() {
 
     /**
      * Annotations on the module.
+     *
+     * Currently, Kotlin does not provide functionality to specify annotations on modules.
      */
+    @Deprecated("This list is always empty and will be removed", level = DeprecationLevel.WARNING)
     val annotations: MutableList<KmAnnotation> = ArrayList(0)
 
     /**