dmdtask: Support MARC 856 to determine identifiers, decommission older methods.

[RussellMcOrmond]

The descriptive metadata loader currently supports looking up identifiers in MARC in 3 different ways:

"marc490"

• https://www.loc.gov/marc/bibliographic/bd490.html
• 490$3 is joined with 490$v with underlines if $3 exists, otherwise use 490$v
• Only a partial identifier, and a prefix needs to be added

"oocihm"

• like "marc490" except change all "-" to underline, and strip anything that isn't a number or underline
• Only a partial identifier, and a prefix needs to be added

"ooe"

• https://www.loc.gov/marc/bibliographic/bd035.html
• use 035$a , skipping the first character.
• Only a partial identifier, and a prefix needs to be added

These were allays a hack, using identifiers created for other purposes to link to identifiers used by the software we are using to provide patron access. These other fields regularly have incomplete identifiers ("CIHM numbers", etc), or otherwise custom as was done for "oocihm" and "ooe" when modifying the record to match current technology enabled better interoperability.

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Ideal is if we move entirely to using the "856 - Electronic Location and Access" field, which needs to be encoded in our records for other purposes anyway. This is likely what we'll need in the future, such as if we adopt and integrate FOLIO and Blacklight.

https://www.loc.gov/marc/bibliographic/bd856.html

What our software would do:

• Loop through any 856 fields (there can and often should be several)
• Look for specific patterns in 856$u that would match content which we would host
  • "*.canadiana.ca/view/{$slug}" (with or without "/{index}" appended at the end
  • "https://n2t.net/ark:{$NOID}" , where NAAN=69429
  • "*.canadiana.ca/ark:{$NOID}" , where NAAN=69429
  • Likely more identifier schemes used in the future
• If there are multiple matches, be helpful in detecting if all the identifiers point to the same Access object and report otherwise.
• Report back the slug that is referenced, which what staff would see in the existing https://access.canadiana.ca/dmd interface.
• Ideally if both MARC and DC CSV files use full Slug identifiers, the added step of optionally adding a prefix can be removed from https://access.canadiana.ca/dmd