feat: Type and Query complexity callbacks

[mbuhot]

Resolves #270

A custom complexity callback can be provided for a type to be used when that type is resolved through a relationship.

A query-level complexity callback applies when the resource has a top-level query in the schema.

Contributor checklist

• Bug fixes include regression tests
• Features include unit/acceptance tests

[zachdaniel]

Suggested change

	type: :mod_arg,
	type: :mfa,

I think we should make these MFAs.

[zachdaniel]

Looks great! I think we should make these MFAs instead of just mod/fun pairs (hardcoded args get prepended to our arguments). That allows better reuse, i.e complexity {MyApp.Complexity, :complexity, [__MODULE__, :very_complex]} etc.

[mbuhot]

@zachdaniel I'm having some trouble forwarding the MFA through to Absinthe:

 2) test custom complexity calculation (AshGraphql.ReadTest)
     test/read_test.exs:424
     ** (Absinthe.AnalysisError) Invalid value returned from complexity analyzer.

     Analyzing field:

       sponsoredComments

     Defined at:

       /Users/michaelbuhot/src/ash-project/ash_graphql/lib/resource/resource.ex:4338

     Got value:

         {AshGraphql.Test.SponsoredComment, :query_complexity, []}

     The complexity value must be a non negative integer.

It looks like only functions, {mod, fun} tuples and constants are supported:

https://github.com/absinthe-graphql/absinthe/blob/main/lib/absinthe/phase/document/complexity/analysis.ex#L107-L129

[zachdaniel]

Ah, right you are. I had a similar complication at some point in the past and did some super hacky shit to get around it. In that case, never mind 😄

[zachdaniel]

Please run mix docs and mix spark.formatter and mix docs and commit the result.