Modify intermediate representation to support normalized Gregorian and Hijri dates

[jacobthill]

Currently the application profile specifies one date value cho_date. To implement the Blacklight Date Range plugin, we will need date ranges in a multivalued field of integers that are stored and indexed. An example for a date range from 1950-1960 years: fake_year_tisim: [1950, 1951, 1952, 1953, 1954, 1955, 1956, 1957, 1958, 1959, 1960]. BCE years will be represented as negative numbers.

We also need a field to store Hijri calendar values.

Requirements:

• [x] add cho_date_norm to the IR to store the normalized array of years
• [ ] add cho_date_hijri field to the data model

[aaron-collier]

Note: IR is defined in https://github.com/sul-dlss/dlme-transform/blob/master/lib/dlme_json_schema.rb