Support ingress from multiple rippled instances to source validations

[pkcs8]

Requested by Rabbit - One standalone hermes instance connects to a single rippled server only. Sourcing validations from multiple rippled servers can provide better visibility of the network.

[pkcs8]

@CrypticRabbit It is possible to run the standalone ingress processors by passing RIPPLED_URL environment variable.

[xrpscan@xrpscan-unstable hermes]$ RIPPLED_URL='wss://xrplcluster.com' node dist/cmd/ingress
[Hermes] info [mongod] Connected: mongodb://localhost:27017/hermes_prod
[Hermes] info [xrpl] Connected: wss://xrplcluster.com
[Hermes] info [ingress] Ingressing validation messages from wss://xrplcluster.com
^C
[xrpscan@xrpscan-unstable hermes]$ RIPPLED_URL='wss://xrpl.ws' node dist/cmd/ingress
[Hermes] info [mongod] Connected: mongodb://localhost:27017/hermes_prod
[Hermes] info [xrpl] Connected: wss://xrpl.ws
[Hermes] info [ingress] Ingressing validation messages from wss://xrpl.ws

Along with the ingress startup script available at bin/ingress.sh, it should be possible to run multiple ingress processors that source validations from multiple rippled servers. Please let me know if this setup works.

[jscottbranson]

Thanks so much, I'll give that a try once I get my node functioning (maybe after Apex).