KT-37587 Karma. Support dynamically created webpack configs

libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/targets/js/testing/karma/KotlinKarma.kt

@@ -154,7 +154,7 @@ class KotlinKarma(override val compilation: KotlinJsCompilation) :
         requiredDependencies.add(versions.webpack)
 
         val webpackConfigWriter = KotlinWebpackConfig(
-            configDirectory = project.projectDir.resolve("webpack.config.d").takeIf { it.isDirectory },
+            configDirectory = project.projectDir.resolve("webpack.config.d"),
             sourceMaps = true,
             devtool = null,
             export = false,

libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/targets/js/webpack/KotlinWebpack.kt

@@ -108,7 +108,7 @@ open class KotlinWebpack : DefaultTask(), RequiresNpmDependencies {
         get() = destinationDirectory.resolve(outputFileName)
 
     open val configDirectory: File?
-        @Optional @InputDirectory get() = project.projectDir.resolve("webpack.config.d").takeIf { it.isDirectory }
+        @Optional @InputDirectory get() = project.projectDir.resolve("webpack.config.d")
 
     @Input
     var report: Boolean = false

libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/targets/js/webpack/KotlinWebpackConfig.kt

@@ -141,7 +141,7 @@ data class KotlinWebpackConfig(
     }
 
     private fun Appendable.appendFromConfigDir() {
-        if (configDirectory == null) return
+        if (configDirectory == null || !configDirectory.isDirectory) return
 
         appendln()
         appendConfigsFromDir(configDirectory)