Store Effective Copy Number

This was split off of UXPROD-1626 (Implement effective logic for call number in Holdings record and inherited to Item records) as it was not completed in Q4 2019, as planned.

Context:
There are a number of data elements that exist on both the holding and item record in inventory:

• Call number type - UXPROD-2171
• Call number prefix - Completed in Q4 2019 UXPROD-1626
• Call number - Completed in Q4 2019 UXPROD-1626
• Call number suffix - Completed in Q4 2019 UXPROD-1626
• Copy number - In scope for this feature

For these elements, the item record should inherit the data from the holding record unless something different has been specified in the item record. This resulting "effective" data is, then, the data that actually matters for the item. This data needs to be stored, as opposed to being calculated on the fly if:
1. It will be used for searching
2. It will be used for sorting
3. It needs to be available in reporting

Scope:
The scope of this feature is to store Effective copy number. Please note that:

• Effective copy number is not needed for Call number searching (which will act on Effective prefix, Effective call number and Effective suffix only see UIIN-858)
• Effective copy number is not needed for Call number sorting (which will act on Effective call number only see UXPROD-2002)
• The main reason for storing this data in the item record at this point would be so that it is easily available for external reporting.

Use Cases:
Use cases for when the item would need to inherit copy number from the holding record (more to be added):

1. One scenario would be multi-volume sets, which could include serial runs. Usually a copy of a multi-volume set will all shelve together, have the same copy number, and would be collected under one holding record. Let's say we have "My Magnum Opus" in three volumes, copy 1 shelves in the Main Library and copy 2 shelves in the Science Library. So there would be one holding record for copy 1 with item records for the three volumes, and another holding record for copy 2, also with three item records. For manual operations, assigning the copy number at the holding level might be less error-prone than duplicating at the item level. (from tod, University of Chicago)
2. One institution (Chicago?) has Chinese language materials that are very large multi-volume sets (300 volumes). They are all the same copy, just 300 different volumes. In this case, putting the copy on the holdings record saves a huge amount of data entry.
3. Conceptually you want to group issues with the set that makes up copy 2
4. See MM SIG discussion here 56:59 to hear full discussion https://drive.google.com/file/d/1NP190uh_M9XCQjGcxV_y5owx4wqUnBjJ/view?usp=sharing

Overall: At the broadest level, keeping the same inheritance logic for all the elements of the effective call number simply makes the most sense, both because it is consistent and because it provides the greatest flexibility for institutions to use copy number in different ways depending on their needs. (from dbottorff, University of Chicago)

Stories Needed:

• Store effective copy number on item record - MODINVSTOR-362
• Make it possible to display effective copy number on item record - MODINV-TBD
• Provide effective copy number for requests and loans - CIRC-570
• Update Effective call number string wherever it displays (Request details, Item details etc) - Stories TBD
• Update Call number data in CSV exports (Hold shelf clearance report etc) - Stories TBD