[Delivers #41570081 #42025921] Accession form redesign

A few things in this one...

- remove the tree from the Accession edit form.  Spawning an Resource now redirects to the resource form -- a "Return to Accession" link is provided in the breadcrumb to allow return to the Accession context once the resource has been saved.

- Refactor "form_changed" javascript into a separate resource.  I've done this so we can check for changes on the form upon window.unload on any form (I'm yet to include this in all forms -- will do this soon).

- Introduce a record-toolbar to hold all record based actions (including edit, spawn, suppress).  

- Moved "Finish Editing" to the tree pane toolbar.

- Introduce "Loading..." message when navigating between nodes in tree views

- Fix "Resource Created" flash message not sticking when redirected to the resource edit form.