rusk-wallet: display current synced block height during sync

[HDauven]

Summary

The UX around syncing will confuse a lot of people. The last known block height is not shown to the user, and not updated, making it hard to figure out how syncing is actually taking place. Adding this would make the syncing process more transparent.

Possible solution design or implementation

For interactive mode, update the block height value in a designated place.

For non-interactive, the value could be updated on an interval and displayed during syncing.