feat: include builtin predicate functions in GraphQL filter schema

[nallwhy]

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• Bug fixes include regression tests
• Chores
• Documentation changes
• Features include unit/acceptance tests
• Refactoring
• Update dependencies

Summary

• Include Ash.Filter.builtin_functions() alongside builtin_operators() in filter type generation for both attributes and calculations
• Update the filterable_fields verifier to also recognize builtin function names (e.g. :contains) as valid operator entries

Problem

Ash.Filter.builtin_functions() returns predicate functions like Contains and IsNil, but they were not included in the GraphQL filter schema generation pipeline. Only Ash.Filter.builtin_operators() and Ash.DataLayer.functions() were used, so functions like contains never appeared in filter input types.

Breaking change

This adds new filter input fields (e.g. contains) to all string/applicable filter types by default. Existing users whose clients rely on strict schema validation may see unexpected fields.

To restrict filters to the previous set, use filterable_fields with explicit operator allowlists:

filterable_fields [:name, email: [:eq, :in, :less_than, :greater_than]]

[Copilot]

Pull request overview

This PR fixes a gap in the GraphQL filter schema generation: Ash.Filter.builtin_functions() (which returns predicate functions like Contains and IsNil) was not being included alongside Ash.Filter.builtin_operators() when building filter input types. As a result, functions like contains never appeared in generated filter schemas.

Changes:

• Added Ash.Filter.builtin_functions() to the operator sources used in filter_type/3 (for attributes/aggregates) and calculation_filter_inputs/2 (for calculations) in resource.ex
• Updated the VerifyFilterableFields verifier to also accept builtin function names as valid operator entries in filterable_fields
• Added a regression test asserting contains appears in the TagFilterName input type for a string field

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
lib/resource/resource.ex	Adds builtin_functions() to the predicate sources for both attribute/aggregate and calculation filter type generation; also removes trailing whitespace in an unrelated warning string
lib/resource/verifiers/verify_filterable_fields.ex	Includes builtin_functions() in the set of valid operator names during compile-time validation of filterable_fields
test/filter_sort_test.exs	Adds an assertion that contains appears in the generated TagFilterName filter input type

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[zachdaniel]

🚀 Thank you for your contribution! 🚀