Payroll - App settings

[leolower]

As discussed with @jounih @sohkai and @bingen our team at Protofire has prepared a set of screen designs for a few additional features.

Payroll settings button on the top right

Set price feed

Set exchange rate expiry time

Set allowed tokens

We can start implementing these features right away as we are finishing our last tasks for the payroll app.

cc @gabitoesmiapodo