OCLC numbers for 7xx processing

[kirkhess]

The 7xx fields should process OCLC control numbers w/ bf:Local identifiers into the subfield $w like LCCNs not in the $o which is for actual local identifiers.

The way it seems to work now is they only process correctly if they are bf:Identifiers w/o a subclass, and that have an agent with a bf:code and no uri.

Correct:
(OCoLC)2256995

Aka the 777 produced by this exemplar shape:

<bf:identifiedBy>
    <bf:Identifier>
        <rdf:value>2256995</rdf:value>
        <bf:assigner>
            <bf:Agent>
                <bf:code>OCoLC</bf:code>
            </bf:Agent>
        </bf:assigner>
    </bf:Identifier>
</bf:identifiedBy>

But if you go to the instance in id (https://id.loc.gov/resources/instances/11165447.html) it has this shape:

    <bf:identifiedBy>
      <bf:Local>
	<rdf:value>ocm02256995 </rdf:value>
	<bf:assigner>
	  <bf:Agent rdf:about="http://id.loc.gov/vocabulary/organizations/ocolc"/>
	</bf:assigner>
      </bf:Local>
    </bf:identifiedBy>

If you are 'getting' bf for processing linking fields, you would probably use the 2nd form so the logic should know about processing this shape as well:
prefix (OCoLC)
concatenated with the rdf:value,
formatted as a number so no leading letters and no leading zeros.