Add -Xuse-mixed-named-arguments compiler flag

That flags enables MixedNamedArgumentsInTheirOwnPosition feature
  (see #KT-7745) without experimental warning

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

@@ -307,6 +307,12 @@ abstract class CommonCompilerArguments : CommonToolArguments() {
     )
     var useFir: Boolean by FreezableVar(false)
 
+    @Argument(
+        value = "-Xuse-mixed-named-arguments",
+        description = "Enable Support named arguments in their own position even if the result appears as mixed"
+    )
+    val useMixedNamedArguments: Boolean by FreezableVar(false)
+
     @Argument(value = "-Xdisable-default-scripting-plugin", description = "Do not enable scripting plugin by default")
     var disableDefaultScriptingPlugin: Boolean by FreezableVar(false)
 
@@ -369,6 +375,10 @@ abstract class CommonCompilerArguments : CommonToolArguments() {
                 put(LanguageFeature.ProperIeee754Comparisons, LanguageFeature.State.ENABLED)
             }
 
+            if (useMixedNamedArguments) {
+                put(LanguageFeature.MixedNamedArgumentsInTheirOwnPosition, LanguageFeature.State.ENABLED)
+            }
+
             if (progressiveMode) {
                 LanguageFeature.values().filter { it.kind.enabledInProgressiveMode }.forEach {
                     // Don't overwrite other settings: users may want to turn off some particular