* add bf16 gemms for gfx11/gfx12
* reduce the input values in test_gemm
* add int8 wmma gemm instances for gfx11/gfx12
* add example gemm_wmma_int8
* fix bug in gemm_wmma_int8 test
* increase bf16 gemm test tolerance
* update the dates and clean-up commented-out instances