feature: CBOR Tag 24 Support - Encoded CBOR data item

[sargun]

Is your feature request related to a problem? Please describe.
Encoded CBOR data item nests serialized CBOR within itself as a byte string. This is useful from a performance perspective, as decoding can be deferred to a later stage. In addition, because byte strings are length prefixed, you can seek past entire chunks (say a large map) of CBOR that you don't want to parse / read.

Describe the solution you'd like
Encoded CBOR data item support for encoding and decoding.

Describe alternatives you've considered
I can do this "by hand", by encoding CBOR manually, telling it my item is type 24, and then adding it to my structure

Additional context
See this part of the CBOR spec / RFC: https://tools.ietf.org/html/rfc8949#section-3.4.5.1

[extemporalgenome]

What would the implemented behavior be? Decode into any would yield a validated cbor.RawMessage when encountering Tag 24 perhaps?

A Tag 24 CBOR value corresponding to a struct field should probably just eagerly decode anyways, unless the field type was cbor.RawMessage (thus the tag would be ignored unless decoding into any)?