Activity page - graph: display graph (even when multiple currencies are published)

[stevieflow]

We know that graphs on an activity page help people see the data - eg:

However, a common feedback is when a graph doesn't render - for example this activity

The Incoming Fund does graph, as there is only one:

The Disbursements do not, as three are GBP whereas one is in USD:

We know that d-portal converts all financial data to USD - but it may not be as simple as "display a graph in USD for all activities" - particularly as this example activity has : default-currency="GBP"

To fix this issue, I guess there are two options:

• When an activity has more than one currency, display the graphs in USD (and provide an onscreen note)
• When an activity has more than one currency, display the graphs in the activity default-currency (assuming that is provided, and conversions can be made)