Show USD alongside local currency in seller admin

[axadrn]

When a purchase happens in a non-USD currency, the Polar seller admin currently shows only the local currency amount.

As a seller, it would be very helpful to always display the USD equivalent alongside the local currency everywhere revenue is shown in the admin.

This makes it possible to understand revenue at a glance without manual conversion.

Example:
€49 ($53.12) instead of just €49