[K/JS] Enable identifiers escaping by default in 2.1 version ^KT-31799 Fixed

compiler/testData/diagnostics/testsWithJsStdLib/name/illegalName.kt

@@ -1,3 +1,4 @@
+// !LANGUAGE: -JsAllowInvalidCharsIdentifiersEscaping
 // FIR_IDENTICAL
 private fun ` .private `(): String = TODO("")
 

compiler/testData/diagnostics/testsWithJsStdLib/name/illegalPackageName.kt

@@ -1,3 +1,4 @@
+// !LANGUAGE: -JsAllowInvalidCharsIdentifiersEscaping
 // FIR_IDENTICAL
 // FILE: slashes.kt
 package a.<!INVALID_CHARACTERS!>`//`<!>.b.<!INVALID_CHARACTERS!>`/`<!>.c

compiler/util/src/org/jetbrains/kotlin/config/LanguageVersionSettings.kt

@@ -308,6 +308,7 @@ enum class LanguageFeature(
     MangleCallsToJavaMethodsWithValueClasses(KOTLIN_2_0, kind = OTHER), // KT-55945
     ForbidInferringTypeVariablesIntoEmptyIntersection(KOTLIN_2_0, kind = BUG_FIX), // KT-51221
     ProhibitDefaultArgumentsInExpectActualizedByFakeOverride(KOTLIN_2_0, kind = BUG_FIX), // KT-62036
+    JsAllowInvalidCharsIdentifiersEscaping(sinceVersion = KOTLIN_2_1, kind = OTHER), // KT-31799
 
     // 2.1
 
@@ -362,7 +363,6 @@ enum class LanguageFeature(
     ProhibitAllMultipleDefaultsInheritedFromSupertypes(sinceVersion = null, kind = BUG_FIX),
     ExplicitBackingFields(sinceVersion = null, kind = UNSTABLE_FEATURE),
     FunctionalTypeWithExtensionAsSupertype(sinceVersion = null),
-    JsAllowInvalidCharsIdentifiersEscaping(sinceVersion = null, kind = UNSTABLE_FEATURE),
     JsAllowValueClassesInExternals(sinceVersion = null, kind = OTHER),
     ContextReceivers(sinceVersion = null),
     ValueClasses(sinceVersion = null, kind = UNSTABLE_FEATURE),