[FR] Add all Result types and higher level Client functions to ./api package

[AdamSLevy]

Currently the api package has all of the Params types for querying the fatd API methods, but not all of the results are put into dedicated types.

Ideally all Params and Results types will be defined, and well documented.

Higher level functions on the provided Client that use the proper Params and Results types are also desired. These functions may then be used by fat-cli.