Migrate Experimental->RequiresOptIn in project sources

compiler/cli/cli-js-klib/src/GenerateJsIrKlib.kt

@@ -41,9 +41,9 @@ fun buildConfiguration(environment: KotlinCoreEnvironment, moduleName: String):
         ),
         analysisFlags = mapOf(
             AnalysisFlags.useExperimental to listOf(
+                "kotlin.RequiresOptIn",
                 "kotlin.contracts.ExperimentalContracts",
-                "kotlin.Experimental",
-                "kotlin.ExperimentalMultiplatform"
+                "kotlin.ExperimentalMultiplatform",
             ),
             AnalysisFlags.allowResultReturnType to true
         )

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/PrivateForInline.kt

@@ -5,5 +5,5 @@
 
 package org.jetbrains.kotlin.fir
 
-@Experimental(level = Experimental.Level.ERROR)
-annotation class PrivateForInline
+@RequiresOptIn(level = RequiresOptIn.Level.ERROR)
+annotation class PrivateForInline

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/dfa/DfaInternals.kt

@@ -5,5 +5,5 @@
 
 package org.jetbrains.kotlin.fir.resolve.dfa
 
-@Experimental
-annotation class DfaInternals
+@RequiresOptIn
+annotation class DfaInternals

compiler/fir/tree/src/org/jetbrains/kotlin/fir/FirImplementationDetail.kt

@@ -5,5 +5,5 @@
 
 package org.jetbrains.kotlin.fir
 
-@Experimental(level = Experimental.Level.ERROR)
-annotation class FirImplementationDetail
+@RequiresOptIn(level = RequiresOptIn.Level.ERROR)
+annotation class FirImplementationDetail

compiler/testData/codegen/box/inference/kt35684.kt

@@ -1,5 +1,5 @@
 // !LANGUAGE: +NewInference
-// !USE_EXPERIMENTAL: kotlin.Experimental
+// !USE_EXPERIMENTAL: kotlin.RequiresOptIn
 // WITH_RUNTIME
 
 // ISSUE: KT-35684

compiler/testData/diagnostics/testsWithStdLib/coroutines/inference/variableOfAFunctionTypeCall.kt

@@ -1,4 +1,4 @@
-// !USE_EXPERIMENTAL: kotlin.Experimental
+// !USE_EXPERIMENTAL: kotlin.RequiresOptIn
 // !DIAGNOSTICS: -UNUSED_EXPRESSION -UNUSED_PARAMETER -UNUSED_VARIABLE
 
 @file:OptIn(ExperimentalTypeInference::class)