* Initial working version of comment frontend in edit view
* Make comment js text translatable
* Add comment icon
* Basic hardcoded comment adding widget
* Create widget object and register it with the comment app to subscribe to updates about related annotations and whether comments are shown
* Add data-contentpath attributes to field (and data-contentpath-disabled to fields which prevent a stable contentpath existing at this point - ie ListBlock block positions are not uniquely identified), and to ensure newly generated streamfield blocks also have a stable contentpath identifiable from the frontend, make streamfield uuids generate clientside
* Make comments detect new contentpaths, and move hardcoded comment widget on chooser template into js initialisation, also making new comment buttons init properly in new streamfield blocks
* Fix tests to expect contentpaths
* Remove two step comment widget initialisation, and replace with stored callbacks for widgets that try to initialise themselves before the comment app itself. Refactor widgets to receive the makeComment function directly from the commenting system via an onRegister method to accommodate this
* Use object argument instead of positional for FieldLevelCommentWidget constructor
* Use json_script to pass author to the comments system
