Add js generate externals collecting statistics

#KT-39995 Fixed

idea/idea-core/src/org/jetbrains/kotlin/idea/statistics/FUSEventGroups.kt

@@ -35,6 +35,7 @@ enum class GradleStatisticsEvents {
     Kapt,
     CompilerPlugins,
     MPP,
+    JS,
     Libraries,
     GradleConfiguration,
     ComponentVersions,

idea/idea-gradle/src/org/jetbrains/kotlin/idea/statistics/KotlinGradleFUSLogger.kt

@@ -99,6 +99,11 @@ class KotlinGradleFUSLogger : StartupActivity, DumbAware, Runnable {
                 StringMetrics.JVM_DEFAULTS
             )
 
+            container.log(
+                GradleStatisticsEvents.JS,
+                BooleanMetrics.JS_GENERATE_EXTERNALS
+            )
+
             container.log(
                 GradleStatisticsEvents.MPP,
                 StringMetrics.MPP_PLATFORMS,