ethexe: support duplicate commitments sent over network

[grishasobol]

Problem

Presently we can receive this warn in case we tries to publish the same message twice over network

libp2p_gossipsub::behaviour] Not publishing a message that has already been published message=ba11c2b9c7189e00

This can be obstructing behaviour in case of some malfunctions in ethexe network. For example after publishing some code commitment in network, sequencer aborts execution. After restarting the same code commitment should be sent from validators to sequencer once more.

Possible Solution

• Append salt in message in network crate (ethexe_network)
• Append salt in message in main commitments logic (currently is ethexe_cli::service)