Ash

TODO: Add description

TODO LIST (in no order)

Add central API configuration DSL api do ... end
- Use this for default_page_size and max_page_size
Make our router cabaple of describing its routes in mix phx.routes Chris McCord says that we could probably power that, seeing as phoenix controls both APIs, and that capability could be added to Plug.Router
Finish the serializer
Make primary key type configurable
Make a DSL for join tables to support complex validation/hooks into how they work, support more than just table names in join_through
DSL level validations! Things like includes validating that their chain exists. All DSL structs should be strictly validated when they are created.
Especially at compile time, we should never ignore or skip invalid options. If an option is present and invalid, an error is raised.
break up the Ash module
Wire up/formalize the error handling
Ensure that errors are properly propagated up from the data_layer behaviour, and every operation is allowed to fail
figure out the ecto schema warning