Generate alive message on the fast chain and send a tx to parachain

[khssnv]

• Message definition from Define alive message structure #144.
• Generate the message reading and aggregating GRANDPA votes together with the block hash.
• Send the message from the fast chain to parachain.

[zotho]

One option for this is to reuse GRANDPA Finality Relay for sending justifications to SPIN pallet:
https://github.com/QuantumFusion-network/polkadot-sdk/tree/master/bridges/relays/finality

[khssnv]

Estimated execution time is 1 week.

[zotho]

Blocker: qf-solonode doesn't have GRANDPA RPC enabled.

See Polkadot RPC example

[zotho]

Deprioritized. Switched to: #180

[zotho]

On hold. Working on documentation #290