Create a new binary `zebra-scanner`

[oxarbitrage]

We want to create a new binary zebra-scanner inside the zebra-scan crate.

This should call zebra_scanner::spawn_init with the ReadState::init(https://github.com/ZcashFoundation/zebra/issues/8520) as the state argument and the last chain from the database as the ChainTipChange(https://github.com/ZcashFoundation/zebra/issues/8580) argument.

The new process should start the scanning and the grpc server to interact with it. Scanner program will run until ctrl-c.

When we get into the details of the non-finalized change we might want to check an RPC endpoint to shut down too.