network-container-start: await healthy network by default

[chadoh]

What problem does your feature solve?

When I run

stellar network container start local

I always, every single time I personally do this, don't want the network to be considered "started" until it's actually healthy.

Right now, I need to manually check if it's healthy, with an ugly curl command like

curl -s -X POST "http://localhost:8000/rpc" \
  -H "Content-Type: application/json" \
  -d '{ "jsonrpc": "2.0", "id": 8675309, "method": "getHealth" }' \
  | sed 's/.*"status":"\([^"]*\)".*/\1/'

Right after stellar network container start returns me to my prompt, this command will tell me "502: Bad Gateway". Then it will tell me "data stores not yet initialized" for a minute or so. Then, finally, it just says "healthy".

What would you like to see?

I don't want to be returned to my prompt until the network is healthy.

It would be nice to have some sort of loader, and maybe a status message. "Starting http...", "Initializing data stores...".

What alternatives are there?

If there's some edge case I'm unaware of in which it would be useful for people to have a partially-started local network, then we could also provide a --no-wait flag.