Support basic smeshing use case

[avive]

Repro Steps

1. Start full node with default config file.
2. Start smrepl and setup post in smrepl.
3. Follow the instructions in smrepl and update the node's config file.
4. Exit smrepl and restart node.

Result: smeshing will not work as expected (same issue as in smapp).
Expected: smeshing to work as expected.

Motivation

Since smrepl is the only reference client we provide for devnets then this issue is pretty high-priority. It is the only critical issue we have in terms of supporting basic smeshing use case. It is unrealistic to ask devnet users to create by hand the node config file and provide it to the node as a work-around because this solution is not user friendly and quite complex. e.g. user need to use the test-app to figure out which providers are available on his system.

@moshababo @noamnelke

[noamnelke]

Step 1 should not exist. The correct way to run a node should be:

1. Generate a config file (manually or using smrepl).
2. Start the node (manually or using smrepl).

If you do it this way, restarting the node will work just fine.

As you said, we have a tool that provides the system's GPUs when a node is not running - smrepl should use this tool in the "Config generator".