Use -opt-in instead of -Xopt-in in comments and scripts

kotlin-native/endorsedLibraries/kotlinx.cli/build.gradle

@@ -55,7 +55,7 @@ kotlin {
 
         jvm().compilations.all {
             kotlinOptions {
-                freeCompilerArgs = ["-Xopt-in=kotlinx.cli.ExperimentalCli", "-Xopt-in=kotlin.RequiresOptIn"]
+                freeCompilerArgs = ["-opt-in=kotlinx.cli.ExperimentalCli", "-opt-in=kotlin.RequiresOptIn"]
                 suppressWarnings = true
             }
         }
@@ -94,9 +94,9 @@ targetList.each { target ->
         args = [*konanArgs,
                 '-output', outputFile,
                 '-produce', 'library', '-module-name', moduleName,
-                '-Xmulti-platform', '-Xopt-in=kotlinx.cli.ExperimentalCli',
-                '-Xopt-in=kotlin.ExperimentalMultiplatform',
-                '-Werror', '-Xopt-in=kotlin.RequiresOptIn',
+                '-Xmulti-platform', '-opt-in=kotlinx.cli.ExperimentalCli',
+                '-opt-in=kotlin.ExperimentalMultiplatform',
+                '-Werror', '-opt-in=kotlin.RequiresOptIn',
                 commonSrc.absolutePath,
                 "-Xcommon-sources=${commonSrc.absolutePath}",
                 nativeSrc]

kotlin-native/endorsedLibraries/kotlinx.cli/src/main/kotlin/kotlinx/cli/ExperimentalCli.kt

@@ -15,7 +15,7 @@ import kotlin.annotation.AnnotationTarget.*
  *
  * Any usage of a declaration annotated with `@ExperimentalCli` must be accepted either by
  * annotating that usage with the [UseExperimental] annotation, e.g. `@UseExperimental(ExperimentalCli::class)`,
- * or by using the compiler argument `-Xopt-in=kotlinx.cli.ExperimentalCli`.
+ * or by using the compiler argument `-opt-in=kotlinx.cli.ExperimentalCli`.
  */
 @RequiresOptIn("This API is experimental. It may be changed in the future without notice.", RequiresOptIn.Level.WARNING)
 @Retention(AnnotationRetention.BINARY)