Fix: QR Code registered token check

[tuliomir]

In two places the application was trying to check if a token was registered by querying the wallet storage object directly. However, this low level storage does not contain the default token, and that lead to false negative responses.

There are other higher level helper sources that already take these implicit default tokens into consideration: those should be used instead. Namely, the getRegisteredTokens saga helper function and the redux state tokens property.

Acceptance Criteria

• Registered tokens should be read from the helper functions

Security Checklist

• Make sure you do not include new dependencies in the project unless strictly necessary and do not include dev-dependencies as production ones. More dependencies increase the possibility of one of them being hijacked and affecting us.