Deprecate -Xuse-k2 compiler flag in Gradle DSL

^KT-56239 Fixed

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

@@ -298,6 +298,11 @@ abstract class CommonCompilerArguments : CommonToolArguments() {
     )
     var checkStickyPhaseConditions: Boolean by FreezableVar(false)
 
+    @GradleDeprecatedOption(
+        message = "Compiler flag -Xuse-k2 is deprecated; please use language version 2.0 instead",
+        level = DeprecationLevel.WARNING,
+        removeAfter = "2.0.0",
+    )
     @GradleOption(
         DefaultValue.BOOLEAN_FALSE_DEFAULT,
         gradleInputType = GradleInputTypes.INPUT,