Add an unwrapped upgrade script for OCLC-aware control numbers

Add an unwrapped upgrade script for OCLC-aware control numbers

The upgrade script creates the SCN and LCCN search indexes and
populates them using metabib.full_rec as a source; cheating, but
the normalized values will work for non-exact search purposes. Sites can
reingest all of their bibs if they want exact search to work.

Also, refactor maintain_control_numbers() using a suggestion by
Dan Wells to eliminate some duplicate code.

Signed-off-by: Dan Scott <dscott@laurentian.ca>
Signed-off-by: Bill Erickson <berick@esilibrary.com>