Fix bill licence supp source decimal in wrong place

https://eaflood.atlassian.net/browse/WATER-4358

Back again! (see [Fix bill licence charge ref decimal in wrong place](#713))

The Billing & Data team have also spotted that the value shown against a supported source in the `/bill-licences` view has the decimal in the wrong place.

Both the charge reference charge (baseline charge) and Supported source charge are extracted out of the JSON blob the Charging Module service captures from the Rules Service and returns in its response.

Looks like the Rules service returns these in pounds, unlike all other values that are in pence.

This change fixes the issue for supported source charge (and fingers crossed that's it!)