Implement onError proposal

[benjie]

Spec PR: graphql/graphql-spec#1153

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@benjie The latest changes of this PR are available on NPM as
graphql@16.10.0-canary.pr.4364.6b142546832c1283b535908fb8c9a171b2f7cc20
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[JoviDeCroock]

I am not opposed to this but what are we doing with the directive that is present on main/v17?

[JoviDeCroock]

Should we move this to the new options?: object that is in here, could maybe facilitate these experimental things better. Alternatively we stick to a flat config

[benjie]

It's specified to be part of the "GraphQL request", so I would expect it top level. I would consider moving some of the non-request properties to be inside an options object though: fieldResolver, typeResolver, subscribeFieldResolver.

[benjie]

I want to add an introspection field indicating the default error behavior of a schema, so I've moved this to draft.