Monitoring for `node.Store`

[Wondertan]

The Node's Store manages every storage footprint from the node, including KVStores, storage for shares, configs, private keys, and with mainline FS implementation also manages the root folder of the node.

The Store interface should be extended to provide some basic observability over it:

• Disk usage
  • Ideally, with a granularity of what is taking how much
• Total/free space of the underlying FS

On top of that, basic monitoring should be built using async in64 counter from Otel