light-client: test against a real full node in CI

[ebuchman]

We should run the light node against a real full node in CI per #120 (comment)

We already run the RPC integration tests against a local full node, but we're not running the light node against it.

The first and simplest thing to do is to run the light-node against that full node. Since it will just be a 1 validator blockchain that doesn't change, this will not test much of the light-client functionality, but is more about ensuring the light-node init/config/process is working correctly and can sync with a real full node.

Future iterations could introduce a lot more complexity:

• talking to multiple full nodes (where one of the full nodes may be faulty or may serve a fork)
• enabling validator set changes on the chain (this would require other full nodes to actually be set up to be the new validators, even if the light node doesn't talk directly to them!)
• talking to remote full nodes from a live mainnet/testnet Gaia blockchain

Since there's a lot to do re scoping the more complex set ups, let's start with the simplest for now.

[liamsi]

ref: tendermint/tendermint#5087
Context: when new docker images for tendermint-go are published, it should simplify testing against CI slightly.

[ebuchman]

Hey is this done with #431?

[brapse]

Yeah this is done but made a follow up for the binary initiazation process specifically in #445.