AutoFieldWidget support for augmenting pcrud search options

AutoFieldWidget support for augmenting pcrud search options

Adds a new searchOptions attribute to AutoFieldWidget for specifying
additional parameters to pcrud when retrieving linked objects.  The
initial use case is for supporting a "select" list to allow
AutoFieldWidget to retrieve only the display column of a linked object
and not the whole object.

Example:

 // fetch 'remote_field_name' on the remote objects instead of
 // fetching the entire object

 myGrid.overrideWidgetArgs.some_field = {searchOptions :
 {"select":{"some_hint":["remote_field_name"]}}};

Signed-off-by: Bill Erickson <berick@esilibrary.com>