Do not report experimental usage errors in import statements

#KT-25545 Fixed

compiler/testData/diagnostics/testsWithStdLib/experimental/importStatement.kt

@@ -0,0 +1,27 @@
+// !USE_EXPERIMENTAL: kotlin.Experimental
+// FILE: api.kt
+
+package feature.experimental.self
+
+@Experimental
+annotation class ImportedMarker
+
+@ImportedMarker
+object ImportedClass {
+    @ImportedMarker
+    fun importedObjectMember() {}
+}
+
+@ImportedMarker
+fun importedFunction() {}
+
+@ImportedMarker
+val importedProperty = Unit
+
+// FILE: usage.kt
+
+import feature.experimental.self.ImportedMarker
+import feature.experimental.self.ImportedClass
+import feature.experimental.self.importedFunction
+import feature.experimental.self.importedProperty
+import feature.experimental.self.ImportedClass.importedObjectMember