Support both sqlite and postgres in ash application

:thinking: try this instead:

use mix ash.gen.base_resource MyApp.Resource and then modify it to look something like this:

  # use it in the resources like this
  use MyApp.Resource

  defmodule MyApp.Resource do
    defmacro __using__(opts) do
       data_layer = 
         if App.Config.use_sqlite?() do
           AshSqlite.DataLayer
         else
           AshPostgres.DataLayer
         end

       opts = Keyword.put_new(opts, :data_layer, data_layer)

        quote do
          use Ash.Resource, unquote(opts)
        end
      end
    end