Support currency & issuer in Request link:

[WietseWind]

Support currency & issuer in Request link:

https://xumm.app/detect/request:rwietsevLFg8XSmG3bEZzFein1g8RBqWDZ?dt=123&amount=1.337&currency=4555525300000000000000000000000000000000&issuer=rs5hzzF7RzdV2Ub7Fv14Z1ShjuCrnL7FEX

(already part of the Xumm String Reader).

It should always start the pathfinding sign request flow, so users can even pay with something if they don't own the requested currency.

@WietseWind
https://xrpl-labs.canny.io/xumm/p/xumm-payment-link-for-invoices

^^ Treat it as a partial payment request Payload flow