Replace useExperimentalAnnotation with optIn in scripts

kotlin-native/samples/echoServer/build.gradle.kts

@@ -47,6 +47,6 @@ kotlin {
 
     // Enable experimental stdlib API used by the sample.
     sourceSets.all {
-        languageSettings.useExperimentalAnnotation("kotlin.ExperimentalStdlibApi")
+        languageSettings.optIn("kotlin.ExperimentalStdlibApi")
     }
 }

kotlin-native/samples/libcurl/build.gradle.kts

@@ -57,6 +57,6 @@ kotlin {
 
     // Enable experimental stdlib API used by the sample.
     sourceSets.all {
-        languageSettings.useExperimentalAnnotation("kotlin.ExperimentalStdlibApi")
+        languageSettings.optIn("kotlin.ExperimentalStdlibApi")
     }
 }

kotlin-native/samples/videoplayer/build.gradle.kts

@@ -51,6 +51,6 @@ kotlin {
 
     // Enable experimental stdlib API used by the sample.
     sourceSets.all {
-        languageSettings.useExperimentalAnnotation("kotlin.ExperimentalStdlibApi")
+        languageSettings.optIn("kotlin.ExperimentalStdlibApi")
     }
 }

kotlin-native/samples/watchos/build.gradle.kts

@@ -73,7 +73,7 @@ kotlin {
 
     sourceSets {
         all {
-            languageSettings.useExperimentalAnnotation("kotlin.native.SymbolNameIsInternal")
+            languageSettings.optIn("kotlin.native.SymbolNameIsInternal")
         }
     }
 }