[Operator] Add hidet.ops.matmul_cublas operator

[yaoyaoding]

Add hidet.ops.matmul_cublas operator, which uses cuBLAS library.

m, n, k = 1024, 1024, 1024
a = hidet.randn([m, k], dtype='float16', device='cuda') / 32.0
b = hidet.randn([k, n], dtype='float16', device='cuda') / 32.0
c = hidet.ops.matmul_cublas(a, b)
d = hidet.ops.matmul(a, b)

hidet.utils.assert_close(actual=c, expected=d, rtol=1e-2, atol=1e-2)

The generated code source.cu looks like

#include <hidet/runtime/cuda/cublas.h>

// ...

DLL void hidet_launch_0(half * __restrict__ a, half * __restrict__ b, half * __restrict__ c) {
  hidet_cublas_strided_gemm(1, 1024, 1024, 1024, 2, 2, 2, a, b, c, 0, 1048576, 1048576, false, false, 64);
}