Migrate to TAV's COSE and CBOR

[maxtropets]

Implement necessary COSE bits to use CCF's own crypto for signing/verification, in order be flexible and maintain good performance.

• Reuse all CBOR from TAV via FFI
• Small COSE wrappers for TBS and COSE envelopes (can extend current CCF COSE code, which contains COSE-specific header values, etc.
  • The intuition is, COSE-building code knows a lot about COSE and does it's own CBOR anyway, the extra is only packaging the envelope and TBS.
• Once done, tombstone 3rdparty/cose-openssl