Implemented Delete feature in DataGridsManager.py. There is still a bug as DBEngine.delete is not implemented

Improved readability for tests using matcher

src/myfasthtml/controls/TreeView.py

@@ -192,7 +192,7 @@ class TreeView(MultipleInstance):
     if self.conf.icons:
       self._state.icon_config = self.conf.icons
     else:
-      self._state.icon_config = {"folder": "TreeViewFolder"}
+      self._state.icon_config = {"folder": "TreeViewFolder", "file": "TreeViewFile"}
   
   def set_icon_config(self, config: dict[str, str]):
     """
@@ -458,8 +458,9 @@ class TreeView(MultipleInstance):
       ), command=CommandTemplate("TreeView.SaveRename", self.commands.save_rename, args=[node_id]))
     else:
       label_element = mk.label(
-        Span(node.label, cls="mf-treenode-label text-sm"),
+        node.label,
         icon=icon,
+        cls="mf-treenode-label text-sm",
         enable_button=False,
         command=self.commands.select_node(node_id)
       )