Update codegen to use "client" preset

[michaelbromley]

Graphql codegen has a client preset plugin which has the following advantage over the current generic SDK plugin:

• It "automatically" types the graphql operation, so it is explicit in where a particular gql document is actually being used in the app. Makes things more maintainable.
• Less indirection in the API layer. You just pass the operation constant to a fetch function.

This task would involve:

1. Installing the client preset per the docs
2. Updating the codegen config
3. In all the "providers" files, replace the gql template function with a graphql function call.
4. Remove calls to the "sdk" object, and instead pass the query/mutation constants directly to the fetch wrapper.