[CK_BUILDER] Convert convolution traits to a struct with factory functions

[shumway]

The convolution traits for forward XDL kernels were complicated and the design wasn't going to scale.

The previous design had separate convolution traits template class instances for each device kernel instance, and used concepts to try to unify the instantiations.

This PR switches to a non-templated composite struct for ConvTraits, with a separate factory function for each device kernel instance. That way the conversion from instance traits and ConvTraits is explicit and can be handle any special cases an instance might have.

We add explicit unit tests for the helper function and also add a unit test for each factory function.

[Copilot]

Pull request overview

This PR refactors the convolution traits system from a templated class-based design to a struct-based design with explicit factory functions. The previous design used template class instances with concepts for unification, which did not scale well. The new approach uses a non-templated ConvTraits struct populated by device-specific factory functions, making the conversion from instance traits to ConvTraits explicit and maintainable.

Changes:

• Converted ConvTraits from a templated class to a pure data struct
• Added factory functions (instance_to_conv_traits) for each device kernel variant
• Split helper utilities into separate files for better organization
• Updated all tests to use the new factory function approach

Reviewed changes

Copilot reviewed 17 out of 17 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
conv_traits.hpp	Converted from templated class to pure data struct
conv_traits_helpers.hpp	New file containing helper functions for trait extraction
instance_to_conv_traits.hpp	New umbrella header for all factory functions
conv_traits_device_grouped_conv_fwd_multiple_*.hpp	Factory functions for each device kernel variant
instance_traits_device_grouped_conv_fwd_multiple_*.hpp	Added device kernel tag types
unit_instance_to_conv_traits_features.cpp	Unit tests for individual helper functions
unit_instance_to_conv_traits_instances.cpp	Unit tests for factory functions per device kernel
test_conv_traits.cpp	Updated to use new factory function API
Other files	Updated references and imports

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[Snektron]

Is there a reason to not directly construct ConvDescription in instance_to_conv_traits? It seems like this structure and ConvSignatureInfo and ConvAlgorithmInfo hold the same exact fields. Except for the instance_string function, but that should be trivial to add there too.

[shumway]

I've added documentation that should explain the separation of responsibilites. Additionally, note that the include dependencies are simpler with this separation.

[aosewski]

I really like those changes! Just have few ideas and future potential problems. See comment