Improve codegen (typescript)

[kevin-legion]

• [x] Instead of splitting the api function argument as query, params, etc... let's stick to the OpenAPI way, that is only 3 arguments: params, headers, and body
• [x] Convert cases (underscore and dash to camel case)

Regarding the second one, I wonder if we're not going to use the Rust underscore convention in TypeScript as well since it makes the code a bit more consistent for everyone @timnitsas-legion

While at it I'll also drop the last remnants of gRpc