ACQ+Vandelay import/merge user interface components

ACQ+Vandelay import/merge user interface components

Acquisitions support for leveraging Vandelay import/merge controls
for loading ACQ records and/or linking ACQ records to existing
catalog records.

Dev includes:

* General purpose Vandelay input form and merge progress indicator (VLAgent)
* VLAgent is now shown in the following interfaces when a bib load/merge/link action is required:
 * Vendor record upload interface
 * PO creation
 * PO "load bibs and items" action
 * PO activation

Signed-off-by: Bill Erickson <berick@esilibrary.com>
Signed-off-by: Ben Shum <bshum@biblio.org>