Add an ability to switch between old and new J2K via settings window

Before that it was possible to do only via registry

#KT-33371 fixed

idea/performanceTests/org/jetbrains/kotlin/idea/perf/AbstractPerformanceJavaToKotlinCopyPasteConversionTest.kt

@@ -13,6 +13,7 @@ import com.intellij.psi.PsiDocumentManager
 import org.jetbrains.kotlin.idea.KotlinFileType
 import org.jetbrains.kotlin.idea.conversion.copy.AbstractJavaToKotlinCopyPasteConversionTest
 import org.jetbrains.kotlin.idea.conversion.copy.ConvertJavaCopyPasteProcessor
+import org.jetbrains.kotlin.j2k.J2kConverterExtension
 import org.jetbrains.kotlin.test.InTextDirectivesUtils
 import org.jetbrains.kotlin.test.KotlinTestUtils
 import java.io.File
@@ -35,7 +36,7 @@ abstract class AbstractPerformanceJavaToKotlinCopyPasteConversionTest(private va
     override fun setUp() {
         super.setUp()
 
-        Registry.get("kotlin.use.new.j2k").setValue(newJ2K)
+        J2kConverterExtension.isNewJ2k = newJ2K
         val index = j2kIndex()
 
         if (!warmedUp[index]) {