[Gradle, JS] Require source-map-loader with kotlin-source-map-loader

It is WA to download necessary dependencies for source-map-loader

#KT-32721 fixed

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

@@ -202,6 +202,7 @@ class KotlinKarma(override val compilation: KotlinJsCompilation) :
         requiredDependencies.add(versions.webpack)
         requiredDependencies.add(versions.webpackCli)
         requiredDependencies.add(versions.kotlinSourceMapLoader)
+        requiredDependencies.add(versions.sourceMapLoader)
     }
 
     fun useCoverage(

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

@@ -46,6 +46,7 @@ data class KotlinWebpackConfig(
 
             if (sourceMaps) {
                 it.add(versions.kotlinSourceMapLoader)
+                it.add(versions.sourceMapLoader)
             }
 
             if (devServer != null) {