[CK tests] Extend conv GPU reference (#3539)

* test_convnd_fwd

* test_convnd_bwd_data

* test_conv_bwd_data_scale

* test_grouped_convnd_fwd_clamp

* test_grouped_convnd_fwd_scale

* multiple A/B tensors and D tensor for fwd GPU ref

* test_grouped_convnd_fwd_scaleadd_ab

* test_grouped_convnd_fwd_bias_clamp

* test_grouped_convnd_fwd_bilinear

* test_grouped_convnd_fwd_gk_bias_clamp

* Extend GPU reference to enable batchnorm epilogue

* test_grouped_convnd_fwd{,_gk}_bias_bnorm_clamp

* test_grouped_conv_bwd_data_bilinear

* test_grouped_convnd_bwd_weight_bilinear

* Add missing template instantiation

* Perform operations in float in reference

* Slightly increase tolerance for batchnorm profiler

* Revert "Slightly increase tolerance for batchnorm profiler"

This reverts commit a3b247522902c712930369f466c376a6430f4f67.

* Revert "test_grouped_convnd_fwd{,_gk}_bias_bnorm_clamp"

This reverts commit 6da4576060215e1d3e0e79ca355c340d3546363c.

* Revert "Extend GPU reference to enable batchnorm epilogue"

This reverts commit e2f75fa10e80740eddb7a46f0a51aaac74b8f1a5.

* Clarify variable names

* Refactor elementwise ops into helper functions

* Make helpers C++17-compatible