nested token submods should be byte-string wrapped

[laurencelundblade]

Right now, the second type of submod, the embedding of a full signed EAT token inside surrounding token is "direct".

I think it needs to be wrapped in a byte string to make it reasonable to implement. When decoding the surrounding token, the nested token will be returned as a byte string that can be easily passed to the COSE/CWT/EAT decoder as these will typically take a byte string as input.

If it is not a byte string, then you have to convince the CBOR decoder to return the CWT Tag as a byte string even though it is not a byte string or the same or related instance of the CBOR decoder used to decode the outside EAT must be used to decode the inside EAT.

No semantics would change. This is only for a practical consideration of the APIs used for decoding CBOR, COSE, CWT and EAT.

[laurencelundblade]

Fixed with #67