Payments: make product_data a dim and version rows

[SorenSpicknall]

User story / feature request

During the implementation of Littlepay deduplication changes, we considered the idea that (unlike other tables from Littlepay) it may be correct to treat the product_data exports from the vendor as slowly changing type 2 data. Rather than overwriting rows when a new export includes a row with the same unique ID (which we do for other tables, since the latest version of a given row is treated as canonical across all time frames the row was active), we may need to store multiple time-bounded versions of the same row.

Note that, at the time of issue creation, we are not yet 100% certain that this is the most correct path to take. Further investigation is needed.

Acceptance Criteria

If we determine that this path is appropriate, we'll need to create a mapping between rows in the product_data table and rows in other Littlepay tables that reference product_ids, using a similar versioned system to we do for GTFS data.