Add an event that can be fired when an mform is about to be submitted via ajax.
This allows custom field types to perform an action when the form is submitted.
The atto text editor will reset any autosaves when the form is submitted.
This change allows form elements to be overridden with a mustache template.
The template can even listen for form validation errors and supply the JS to
change the look of the form element when there is/isn't a validation error.
Initial support is for all core form elements including:
text, select, selectyesno and checkboxes, groups, dateselector, datetimeselector,
autocomplete, modvisible, advcheckbox, button, duration, filemanager, filepicker, editor, static, grading,
warning, textarea, password, url, submit, questioncategory, recaptcha.
Part of MDL-55071
When nodes are added to the dom, they may need to be re-processed by a JS based
filter. To do this we need to trigger the legacy YUI event filter-content-updated.
To make this easier I added some wrappers to template that will insert the node, run any
JS and trigger the event.
I also changed existing yui code to call the amd function to trigger the event. This way
all jquery and yui listeners will always be notified.
