We did not implement these methods that allow to create a CipherData
from a Cipher.

But we will need them soon to convert more easily paper and contact
to ciphers.

We also complete toFieldData method.

We were converting papers/contacts to CipherResponse because it is the model used by default during the sync.

Here we choose to convert to CipherData instead because :
- it will help us add a fallback to the sync. When papers/contacts sync will fail, we will be able to use the previous papers/contacts stored locally (they are stored as CipherData)
- the conversion is simplier (it involves less classes)
- we can still inject our papers/contacts during the sync thanks to the upsert method

We need the encryption key to convert papers/contacts. So if we try to do a sync when the vault is locked, we will have no papers/contacts. In some case, another sync is triggered when we unvault the lock, but if we unlock the vault when the previous sync is still in progress AND previous sync already passed the papers/contacts conversion (which failed), it can result to empty papers/contacts.

In this case, we want to reuse stored papers/contacts.