Standardize MARC fields for people and institution relationships

[ahankinson]

Person authorities use 500 (Related Personal Name), 510 (Associated Institution), 551 (Geographic name) Institution authorities use 700 (Person), 710 (Related institution), 551 (Place)

~~These should be made consistent and moved to using the 7XX fields for both:~~

• ~~700 (Person relationships)~~
• ~~710 (Institution relationships)~~
• ~~751 (Place / Geographic name relationships)~~

Update: The thinking is now that Institutions should be changed to match people, so both should use 500/510/551.

[jenniferward]

7XX isn't correct in our context because the 7XX fields are for linking to equivalent headings from other systems, which we don't do.

To show relationships, Institution's 700 should be 500, and 710 should be 510.

500 would be a new field in Institutions.

510 is already used, but that data should be moved. See: https://github.com/rism-digital/muscat/issues/1542