Include path in filePath param for preview in the online editor (#3896)

src/main/scala/gitbucket/core/controller/RepositoryViewerController.scala

@@ -174,7 +174,7 @@ trait RepositoryViewerControllerBase extends ControllerBase {
     filename match {
       case Some(f) =>
         helpers.renderMarkup(
-          filePath = List(f),
+          filePath = f.split("/").toList,
           fileContent = params("content"),
           branch = repository.repository.defaultBranch,
           repository = repository,

src/main/twirl/gitbucket/core/repo/editor.scala.html

@@ -215,7 +215,7 @@ $(function(){
         $.post('@helpers.url(repository)/_preview', {
           content          : editor.getValue(),
           enableWikiLink   : false,
-          filename         : $('#newFileName').val(),
+          filename         : $('path').val() + '/' + $('#newFileName').val(),
           enableRefsLink   : false,
           enableLineBreaks : false,
           enableTaskList   : false