Introduce kotlin.ExperimentalStdlibApi annotation for prerelease API

#KT-30174

libraries/stdlib/src/kotlin/annotations/ExperimentalStdlibApi.kt

@@ -0,0 +1,34 @@
+package kotlin
+
+import kotlin.annotation.AnnotationTarget.*
+
+/**
+ * The experimental standard library API marker. The API marked with this annotation is not subject to the
+ * [general compatibility guarantees](https://kotlinlang.org/docs/reference/evolution/components-stability.html) given for the standard library:
+ * the behavior of such API may be changed or the API may be removed completely in any further release.
+ *
+ * > Beware using the annotated API especially if you're developing a library, since your library might become binary incompatible
+ * with the future versions of the standard library.
+ *
+ * Any usage of a declaration annotated with `@ExperimentalStdlibApi` must be accepted either by
+ * annotating that usage with the [UseExperimental] annotation, e.g. `@UseExperimental(ExperimentalStdlibApi::class)`,
+ * or by using the compiler argument `-Xuse-experimental=kotlin.ExperimentalStdlibApi`.
+ */
+@Experimental(level = Experimental.Level.ERROR)
+@Retention(AnnotationRetention.BINARY)
+@Target(
+    CLASS,
+    ANNOTATION_CLASS,
+    PROPERTY,
+    FIELD,
+    LOCAL_VARIABLE,
+    VALUE_PARAMETER,
+    CONSTRUCTOR,
+    FUNCTION,
+    PROPERTY_GETTER,
+    PROPERTY_SETTER,
+    TYPEALIAS
+)
+@ExperimentalStdlibApi
+@SinceKotlin("1.3")  // TODO: Remove experimental status from itself and advance SinceKotlin to 1.4
+public annotation class ExperimentalStdlibApi

libraries/tools/binary-compatibility-validator/reference-public-api/kotlin-stdlib-runtime-merged.txt

@@ -37,6 +37,9 @@ public final class kotlin/Experimental$Level : java/lang/Enum {
 public abstract interface annotation class kotlin/ExperimentalMultiplatform : java/lang/annotation/Annotation {
 }
 
+public abstract interface annotation class kotlin/ExperimentalStdlibApi : java/lang/annotation/Annotation {
+}
+
 public abstract interface annotation class kotlin/ExperimentalUnsignedTypes : java/lang/annotation/Annotation {
 }