rkp: pull out remaining CDDL and make compliant

Extract CDDL from MacedPublicKey.aidl and DeviceInfo.aidl.

Make -70000 optional in `PublicKey`.

Make CDDL compliant with RFC8610:

- Move `bstr` contents for generated data (e.g. `ECDSA(..)`) to comments.
- Fix alternatives in CBOR-encoded bstr instances.

Add more RFC references and unify reference style.

Try to use a standard format to indicate that external files are needed
for the complete CDDL schema.  (Hopefully in the future we might have
tooling that uses these to check the schemas.)

Test: Compile with docs.rs/cddl-cat and https://cddl.anweiss.tech/
Change-Id: Ie1d6c39f1cc0314e312df9205b570b89178ebd16