Mark all Worker-related API as obsolete.

* Explain what obsolete means and why workers are obsolete
* Add some documentation to workers to explain its common pitfalls

^KT-54702


Merge-request: KT-MR-9563
Merged-by: Vsevolod Tolstopyatov <qwwdfsad@gmail.com>

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

@@ -130,3 +130,4 @@ public expect annotation class RefinesInSwift()
 @ExperimentalObjCRefinement
 @SinceKotlin("1.8")
 public expect annotation class ShouldRefineInSwift()
+