Add two fields to Upload

[shirey]

Add two new fields to the Upload entity

The following fields are to support the addition of these fields in the Ingest UI, see ingest-ui#1586. Both fields are optional, so empty/not-present/blank is valid

1. anticipated_complete_upload_month
   - Type: string with format YYYY-MM, e.g 2025-03 (always two digit month)
   • Validation: any month/year including the current month through and including 12/2026. Months prior to the current month or from 1/2027 onward are invalid. This is an optional field so nothing/blank is valid as well.
   • Description: The month that the Upload is anticipated to have all required data uploaded.
2. anticipated_dataset_count
   - Type: numeric/integer
   - Validation blank or a positive integer (> 0) or empty/missing
   - Description: The total number of datasets that this Upload will eventually contain.

[kburke]

#829