Introduce an 'add event' toolbar partial and use this on the accession and resource forms
Disable the keydown event handlers in jstree that were overriding basic keyboard actions (for no reason)
Add add event toolbar action to components and digital objects
Only show add event action in toolbar if record is not suppressed
If an event is suppressed, show a message on the readonly form and redirect to this page when trying to edit the event.

When events are listed on a record (as a linked record), only show the edit action if the event isn't suppressed.
Fix overflow issue when toolbar buttons wrap on narrow screens. Also move merge action into the record-toolbar (so it disables when a record has been edited)