REST API for cached chain registry

[cbrit]

We need either a feature or separate ocular crate in the workspace for hosting a cache of the chain registry with a RESTful API for ocular to query chain and IBC path information. This should be optional as a user may opt to manually configure their chain client and/or read in IBC path data some other way.

[cbrit]

Current design idea:

ocular crate:

• registry-api feature that includes the entire server/handler/caching system
• Written with axum
• Have the option to cache data from a local chain-registry repository clone instead of calling to Github

ocular_cli crate:

• ocular registry start command that runs the above from a CLI context

Splitting it up this way means users can choose to either run the API in a separate process or spin up a thread from within their app.