[Gradle] Add KotlinVersion.DEFAULT

KT-56210

generators/tests/org/jetbrains/kotlin/generators/arguments/kotlinVersionGenerator.kt

@@ -38,6 +38,8 @@ internal fun generateKotlinVersion(
                 println("fun fromVersion(version: String): KotlinVersion =")
                 println("    KotlinVersion.values().firstOrNull { it.version == version }")
                 println("        ?: throw IllegalArgumentException(\"Unknown Kotlin version: ${'$'}version\")")
+                println()
+                println("val DEFAULT = KOTLIN_${LanguageVersion.LATEST_STABLE.major}_${LanguageVersion.LATEST_STABLE.minor}")
             }
             println("}")
         }

libraries/tools/kotlin-gradle-compiler-types/src/generated/kotlin/org/jetbrains/kotlin/gradle/dsl/KotlinVersion.kt

@@ -23,5 +23,7 @@ enum class KotlinVersion(val version: String) {
         fun fromVersion(version: String): KotlinVersion =
             KotlinVersion.values().firstOrNull { it.version == version }
                 ?: throw IllegalArgumentException("Unknown Kotlin version: $version")
+
+        val DEFAULT = KOTLIN_1_9
     }
 }

libraries/tools/kotlin-gradle-plugin-api/api/kotlin-gradle-plugin-api.api

@@ -555,6 +555,7 @@ public final class org/jetbrains/kotlin/gradle/dsl/KotlinVersion : java/lang/Enu
 
 public final class org/jetbrains/kotlin/gradle/dsl/KotlinVersion$Companion {
 	public final fun fromVersion (Ljava/lang/String;)Lorg/jetbrains/kotlin/gradle/dsl/KotlinVersion;
+	public final fun getDEFAULT ()Lorg/jetbrains/kotlin/gradle/dsl/KotlinVersion;
 }
 
 public abstract class org/jetbrains/kotlin/gradle/plugin/AbstractCompileWithDependenciesTracking : org/gradle/api/tasks/compile/AbstractCompile {