Setting default openmp settings for MKL kernels (#19136)
* Change inter op defaults when built with MKL to avoid thread oversubscription
* Bump up default mkl inter_op to be less conservative
* Added default OMP settings that are expected to give reasonable performance when using MKL kernels
* Query CPUID for determining number of hyperthreads per physical core on Intel 64 architectures
* Style fixes
* Buildifier and clang-format style fixes
* Removed use of setenv due to concerns about thread safety