Update network connectivity on selection, and detect if the network becomes reachable/not

[SvenDowideit]

changing networks between working and not-working didn't change the validator.running state, so things didn't match up

it still doesn't notice a state change in the selected network, but at least switching networks means it gets updates,

• detect currently selected network state change, and show it
• make the state ternery - add an unknown - that you get until the first validator state message is returned.

[SvenDowideit]

The real reason i started looking, is that if you have a local validator, and stop it, after that, the unsubscribeprogramchanges fails hard, and from that point, the web3.js code keeps trying ws error: connect ECONNREFUSED 127.0.0.1:8900

which makes me suspect that if we have intermittent network, we're going to notice the resource leak.

2022-03-15T03:54:09.971Z INFO connection failed                                 
2022-03-15T03:54:09.972Z INFO OK                                                method=validator-state running=false
2022-03-15T03:54:09.972Z ERROR ERROR                                             method=accounts name=FetchError
2022-03-15T03:54:09.972Z ERROR Stacktrace:                                       
2022-03-15T03:54:09.972Z ERROR  FetchError: request to http://127.0.0.1:8899/ failed, reason: connect ECONNREFUSED 127.0.0.1:8899
2022-03-15T03:54:09.972Z ERROR      at ClientRequest.<anonymous> (/home/sven/src/cryptoworkbench/solana-workbench/release/app/node_modules/node-fetch/lib/index.js:1491:11)
2022-03-15T03:54:09.972Z ERROR      at ClientRequest.emit (node:events:394:28)   
2022-03-15T03:54:09.972Z ERROR      at ClientRequest.emit (node:domain:470:12)   
2022-03-15T03:54:09.972Z ERROR      at Socket.socketErrorListener (node:_http_client:447:9)
2022-03-15T03:54:09.972Z ERROR      at Socket.emit (node:events:394:28)          
2022-03-15T03:54:09.972Z ERROR      at Socket.emit (node:domain:470:12)          
2022-03-15T03:54:09.972Z ERROR      at emitErrorNT (node:internal/streams/destroy:157:8)
2022-03-15T03:54:09.972Z ERROR      at emitErrorCloseNT (node:internal/streams/destroy:122:3)
2022-03-15T03:54:09.972Z ERROR      at processTicksAndRejections (node:internal/process/task_queues:83:21)
2022-03-15T03:54:10.282Z INFO OK                                                method=unsubscribe-program-changes

this will be dealt with in a different PR - possibly in solana-web3.js?

[nathanleclaire]

Nice, I really like the change in validator state to enum.

Before we double down on program changes, I think we should do some thinking on if it's the right approach. Lately, for instance, I've been wondering why maybe we don't just work our way through the slots (blocks) and store the relevant info in the DB (which programs/accounts are of interest, etc). Then we wouldn't necessarily have this whole fragile subscription model going.

[SvenDowideit]

@nathanleclaire yup, but that's totally for a different PR/issue :)

[nathanleclaire]

LGTM