Automatically generate predefined queries, mutations, and subscriptions

[bradens]

Problem

We had to manually update graphql queries for the "builtin" queries with changes whenever the schema was updated. This was annoying, costly and meant that the sdk was always out of date.

Instead, let's automatically build them.

Caveats:

• This is a breaking change, as the old builtin queries have been replaced.
• We may need to add a way to override the auto generated behavior, we could do this by mixing in these auto generated ones with handcrafted ones.

After this PR lands, we'll support all of the queries, mutations, and subscriptions listed on docs.codex.io via sdk.queries.*, sdk.subscriptions.* and sdk.mutations.*.