Make escaping for json simpler and more consistent in Mako templates
- add escape_json_dumps to escape and json.dumps
- add escape_js_str to escape javascript string
- refactor Studio to use escape_json_dumps in Mako templates
TNL-2646: Escape json.dumps
<nav> elements for the actions a user can perform on a perticular
page contain inaccessible label whic causes screen reader users
confusion regarding to their current navigation.
TNL-1531