dmdtask: Support more than MARC 245$a when extracting "label" field

[RussellMcOrmond]

MARC 245 - Title Statement

We currently only use: $a - Title

Looking at the documentation, I suspect "abc" would be more appropriate.

Unlike with #68, this is a change in the metadata loader and thus encoding only needs to conform to the updated MAP when the loader is used (new records, updates, etc). There is no need to evaluate all records already loaded.

[RussellMcOrmond]

Note that the "label" field being discussed is the IIIF Presentation API label field as encoded in Access Objects in the access CouchDB database.

This is information extracted from the metadata record at the time the record is loaded.

This IIIF field is then used by CAP in specific places (the title with the HTML, the first line after the image is shown, etc)

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\\crkn-nas\wip\_Metadata_Synchronised\analysis\MARC245lists has CSV files to look at to see how labels will look like if the same data was re-loaded.

There is also a more-than-abc.csv file which shows records with values in other fields.

For most of the rows it is a $h value, except for some MARC for ooe.* which has $p ,$6, $n, $f.