Refactor "jstreetable.js" and update the zip renderer

- Remove redundant and not-working customization that modifies the
  "jstree-table-wrapper" style. "jstreetable.js" doesn't provide any
  minimum version so that MFR has to use the full one. The file has
  been refactored with eslint es5 plugin and better docstrings.
- Minor updates for the renderer:
  - Enable cache which was disabled for local test
  - Update column width for file size
  - Set `is_folder` optional (`True` as default)
  - Use closed-folder icon
  - Remove unused assets

Author: cslzchen

mfr/extensions/zip/render.py

@@ -21,7 +21,7 @@ def file_required(self):
 
     @property
     def cache_result(self):
-        return False
+        return True
 
     def render(self):
 
@@ -99,7 +99,7 @@ def obj_list_to_tree(self, obj_list: list) -> List[dict]:
 
         return [tree_root, ]
 
-    def update_node_with_attributes(self, node: dict, obj: ZipInfo, is_folder: bool) -> None:
+    def update_node_with_attributes(self, node: dict, obj: ZipInfo, is_folder: bool=True) -> None:
         """Update details (date, size, icon, etc.) of the node with the given object.
 
         :param node: the node to update