Create "meta-codec" for parsing bns state

[ethanfrey]

Scope: web4-read

We want to allow very flexible queries with iov-core.
With BCP-proxy we have access to json and can build dynamic queries easily.
If we want to allow the same power with a direct connection, we need a way of defining that.

• Define format for "codec definition": protobuf plus json transform plus?
• Write "meta-codec" that takes static files and initializes a chain-specific bcp/bns/??? read proxy
• Test this is compatible with current bcp/bns implementation
• Add type-safety for bcp-basic and bns queries

[webmaster128]

Closing as mostly outdated. There is currently no plan for a meta-codec or we solved that issue differently. BCP-proxy is not developed at the moment.