feat!: remove public key from ed25519 private key

[Erigara]

Description

Before ed25519 private key was represented as concatenation of private key and private key.
After the changes introduced in this PR it is just private key.

Linked issue

Closes #4838

Benefits

Private keys are more compact and doesn't contain unnecessary information.

Downsides

Iroha environments have to be updated.

For reviewers

All actual changes are in:

• crypto/src/lib.rs serialization
• crypto/src/signature/ed25519.rs deserialization

[Erigara]

@BAStos525 this change require changing private keys in the following way:

1. replace private key prefix 802640 -> 802620
2. remove last 64 characters from private key (which correspond to public key)