[Feature] Filesystem reorganization

[kaimast]

Fixes #4013.

This PR adds a new node-data directory that contains all node-specific data (essentially everything but the ledger). This is located at ~/.aleo/storage/node-data-{network_id} for production or ./node-data-{network_id}-{dev} for development nodes. Alternatively, users can also pass a value to --node-data and store the data at a custom path.

At startup, a node will check for any files that indicate that the old storage format is used. In that case, a message is printed in how to migrate, and the node will not start. Additionally, the FAQ in the README contains information on how to migrate.

Alternatively, nodes can also be started with --auto-migrate-node-data to do this automatically. This is not enabled by default out of extra precaution.

[vicsn]

We need to either provide a migration tool (e.g., snarkos migrate) or a document on how to move to the new layout.

I think documentation in the snarkOS README, release and release blog should be sufficient. .current-proposal-cache*, cached_*_peers and jwt_secret_*.txt are all written at every startup/shutdown.

I picked the name node-config as a placeholder, and we can consider changing it.

I think this may not reflect how important it is for validators to keep .current-proposal-cache*. Please bring some alternatives to the next protocol weekly sync.

Should nodes check for the new directory, so that even if --node-config-dir is not passed, the new layout is used?

Given that backups are essentially required are for validators, what about we make it a mandatory flag for --validator nodes so they're forced to think about it. I will be very clear about it in the next release.

[vicsn]

Almost there!

[vicsn]

Note this may need a minor merge to include #4054 once it's ready

[kaimast]

Note this may need a minor merge to include #4054 once it's ready

c8f5891 merged staging include #4054's changes.

[ljedrz]

I like the general direction, there are just a few errors left to iron out, especially this one.

[ljedrz]

Left one last comment, but LGTM otherwise 👍.

[vicsn]

LGTM!