Read contract addresses from deployments.json

[wjmelements]

parse_deployment_output gets the contract addresses from the output text. I think a better approach would be to read them from deployments.json.

Originally posted by @wjmelements in #41

The deployment scripts modify deployments.json, setting addresses for the deployed contracts. It would be simpler to extract the devnet addresses from that.

See FilOzone/filecoin-services#354 and FilOzone/filecoin-services#364

[wjmelements]

Contract names would need to change. For example, service_provider_registry_proxy (to_snake_case("ServiceProviderRegistry Proxy")) would become SERVICE_PROVIDER_REGISTRY_PROXY_ADDRESS

[wjmelements]

One complication is that there are multiple runs. Seems deployments might not happen only once.

[redpanda-f]

This is also part a of #36

[redpanda-f]

The current system parses the stdout and extracts things that way. However, that by design is error prone.
It would be interesting to change it to retrieve form deployments.json yes.