Dashboard: Widget edit: Long widget name does not save or show validation message

Overview:
When a widget is edited and a long title added the changes are not saved when “Save & close” is selected. Instead the Widget Name field rests to show the original.

Steps to Reproduce:

1. In the dashboard app, add a new widget and save it.
2. Edit the widget.
3. Change the Widget Name, paste in the text: "Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum."
4. Select "Save & close"

Expected Results:  

• The user should be prevented from entering a string longer than the maximum length of the widget name into this field (consistent with Agreement Name and License Name)

Actual Results:  
The original Widget Name is displayed, overwriting the change.

Dev task breakdown

• Frontend validation in field
• Backend validation so it errors onSave
• Double check existing behaviour cannot begin with a Widget >255 chars, as this may introduce breaking change.
  • Test both from frontend and curl