FEATURE: UR for Tor Auth Token, and present crypto-request.

[ChristopherA]

Work with @wolfmcnally to define UR & CBOR for a Tor Auth Token, which can be QR'ed or Pasted in the "Add" pane:

In addition, the Add pane can have a QR that does a crypto-request to ask for a Tor Auth Token from a wallet.