Remove generated FE resources, run npm in sbt

Author: grzegorz-bielski

project/Build.scala

@@ -1458,6 +1458,11 @@ object Build {
     def asScala3doc: Project = {
       def generateDocumentation(targets: String, name: String, outDir: String, params: String = "") = Def.taskDyn {
           val projectVersion = version.value
+
+          val frontEndDir = baseDirectory.value / "resources"
+          runProcess(Seq("npm", "install"), wait = true, directory = Some(frontEndDir))
+          runProcess(Seq("npm", "run", "build"), wait = true, directory = Some(frontEndDir))
+
           val sourcesAndRevision = s"-s github://lampepfl/dotty --projectVersion $projectVersion"
           run.in(Compile).toTask(
             s""" -d scala3doc/output/$outDir -t $targets -n "$name" $sourcesAndRevision $params"""