Transactions Report - Add Payment Method ID column to the transactions export

[mordeth]

Description

Introduce a new column titled "Payment Method ID" on the Transactions page and its corresponding CSV export.

As the Payment Method ID is not presently stored in the database, we must initially expand the database and preserve it to enable its display.

[haszari]

@mordeth do you have any more information about where this request/feature idea originated - e.g. are there merchant requests?

If there are more requests for this then we could feed into product backlog; otherwise if it's an internally-generated idea we could potentially close this issue (not an actionable bug).