Allow plaintext for mockQrCodeValue

[berkes]

When we run the app in dev mode, we get the extremely helpful option to paste a QR code (instead of scanning it via a webcam or such).

However, converting a QR binary to a form_encoded requires some hoops to jump through.

While, in most setups, when developing, we have plain-text values behind the QR code available.

E.g. openid://?request_uri=https%3A%2F%2Ffake.example.com%2Fproxy%2Fget-offer%2F3cREDACTED&client_id=did%3Akey%3AzREDACTED

That way, getting a value from an issuer, verifier, etc into the wallet is even easier. Would this be feasible and easy to implement?