DIDComm API Rust vs Python

1. DIDDoc:
- [DONE] **Rust**: add DID field: OK
- DIDDoc services: DIDComm VS all: SOLVED
- create a ticket
- keep all in Rust;
- keep did comm only in Python
- Verification method public key: just str in Python SOLVED
- keep field name public_key
- [DONE] in **Python**: add Enum with key types and VerificationMaterial type
- [DONE] in **Rust**: rename public key enum to verification material
- DIDDoc: verification_methods SOLVED
- [DONE] **Python**: verification_methods

2. Resolvers as separate params SOLVED
- keep impl-dependent

2. DID Resolver: SOLVED
- DID only or DID + DID URL?
DID only
[DONE]**Python**
[DONE] **Rust**

3. Secrets Resolver: SOLVED
- [DONE] **Python** get_keys(self, kids: List[DID_URL])
- **Rust**: get_keys(self, kids: List[DID_URL])

4. Errors
- DIDNotFound VS DIDNotResolvedError: SOLVED
- Have two errors: DIDDocNotResolvedError and DIDUrlNotFoundError? - OK
- [DONE] **Python**: two errors
- [DONE] **Rust**: two errors
- Common DIDCommError SOLVED
- SecretNotFound VS notResolved SOLVED
- [DONE] **Python**: SecretNotFound
- UnsatisfiedConstraintError
[DONE] **Python**
**Rust**

5. hide instead of protect SOLVED
[Done] **Rust**: protect_sender_id

6. Message SOLVED
- Message VS Plaintext
- [DONE]**Python**: Message
- pack/unpack methods of Message OK
- no from prior in **Rust**

7. pack/unpack SOLVED
- forward_headers
**Rust**: check in Rust

8. Forward API: TBD for Rust