[CK_BUILDER] Convert convolution traits to a struct with factory functions (#3547)

* Factor helpers out of conv_traits.hpp

* Create a non-templated conv_traits struct

* Migrate to new instance-specific instance_to_conv_traits functions

* Clean up reflection concepts

* Clean up ConvTraits helpers

* Update testing for convolution traits

This is a lot of cleanup on tests to have verbose coverage of feature
extraction, explicit tests for each supported device kernel, and
simple, readable test code.

* Address reviewer comments and resolve merge conflict