[Gradle, JS] Allow to change destDir only for separate task and name it destinationDir

#KT-38331 fixed

libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/targets/js/dukat/DukatTask.kt

@@ -60,7 +60,7 @@ abstract class DukatTask(
      * Destination directory for files with converted declarations
      */
     @get:OutputDirectory
-    abstract var destDir: File
+    abstract val destinationDir: File
 
     @get:Internal
     internal abstract val considerGeneratingFlag: Boolean
@@ -72,12 +72,12 @@ abstract class DukatTask(
     open fun run() {
         nodeJs.npmResolutionManager.checkRequiredDependencies(this)
 
-        destDir.deleteRecursively()
+        destinationDir.deleteRecursively()
 
         DukatRunner(
             compilation,
             dTsFiles,
-            destDir,
+            destinationDir,
             qualifiedPackageName,
             null,
             operation

libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/targets/js/dukat/IntegratedDukatTask.kt

@@ -8,7 +8,6 @@ package org.jetbrains.kotlin.gradle.targets.js.dukat
 import org.gradle.api.tasks.OutputDirectory
 import org.jetbrains.kotlin.gradle.plugin.mpp.KotlinJsCompilation
 import org.jetbrains.kotlin.gradle.targets.js.npm.npmProject
-import org.jetbrains.kotlin.gradle.utils.property
 import java.io.File
 import javax.inject.Inject
 
@@ -21,9 +20,8 @@ constructor(
     override val considerGeneratingFlag: Boolean = true
 
     @get:OutputDirectory
-    override var destDir: File by property {
-        compilation.npmProject.externalsDir
-    }
+    override val destinationDir: File
+        get() = compilation.npmProject.externalsDir
 
     private val executor by lazy {
         DukatExecutor(nodeJs, dts, compilation.npmProject, true, compareInputs = false)

libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/targets/js/dukat/SeparateDukatTask.kt

@@ -19,7 +19,7 @@ constructor(
     override val considerGeneratingFlag: Boolean = false
 
     @get:OutputDirectory
-    override var destDir: File by property {
+    override var destinationDir: File by property {
         project.projectDir.resolve("externals")
     }
 }