KT-64385 Enable K2 KAPT by default

Also adds support for front-end compiler plugins in Kapt

compiler/cli/cli-common/gen/org/jetbrains/kotlin/cli/common/arguments/K2JVMCompilerArgumentsCopyGenerated.kt

@@ -78,7 +78,6 @@ fun copyK2JVMCompilerArguments(from: K2JVMCompilerArguments, to: K2JVMCompilerAr
     to.typeEnhancementImprovementsInStrictMode = from.typeEnhancementImprovementsInStrictMode
     to.useFastJarFileSystem = from.useFastJarFileSystem
     to.useJavac = from.useJavac
-    to.useKapt4 = from.useKapt4
     to.useOldBackend = from.useOldBackend
     to.useOldClassFilesReading = from.useOldClassFilesReading
     to.useOldInlineClassesManglingScheme = from.useOldInlineClassesManglingScheme

compiler/cli/cli-common/src/org/jetbrains/kotlin/cli/common/arguments/K2JVMCompilerArguments.kt

@@ -845,16 +845,6 @@ This option is deprecated and will be deleted in future versions."""
             field = value
         }
 
-    @Argument(
-        value = "-Xuse-kapt4",
-        description = "Enable the experimental KAPT 4."
-    )
-    var useKapt4 = false
-        set(value) {
-            checkFrozen()
-            field = value
-        }
-
     override fun configureAnalysisFlags(collector: MessageCollector, languageVersion: LanguageVersion): MutableMap<AnalysisFlag<*>, Any> {
         val result = super.configureAnalysisFlags(collector, languageVersion)
         result[JvmAnalysisFlags.strictMetadataVersionSemantics] = strictMetadataVersionSemantics