ROCm support

[chhwang]

Add supports for AMD's CDNA2 architecture. Multi-GPU execution is not yet supported for AMD GPUs.

[codecov]

Codecov Report

Merging #162 (f9550db) into main (d877ea2) will increase coverage by 0.24%.
The diff coverage is 82.94%.

❗ Current head f9550db differs from pull request most recent head 875304d. Consider uploading reports for the commit 875304d to get more accurate results

@@            Coverage Diff             @@
##             main     #162      +/-   ##
==========================================
+ Coverage   70.56%   70.81%   +0.24%     
==========================================
  Files          92       93       +1     
  Lines        6955     7075     +120     
==========================================
+ Hits         4908     5010     +102     
- Misses       2047     2065      +18     

Files	Coverage Δ
ark/gpu/gpu_kernel.h	100.00% <ø> (ø)
ark/gpu/gpu_mem.h	100.00% <ø> (ø)
ark/gpu/gpu_mgr.h	100.00% <ø> (ø)
ark/ops/ops_add.cc	90.47% <ø> (ø)
ark/ops/ops_cast.cc	76.92% <ø> (ø)
ark/ops/ops_common.h	100.00% <ø> (ø)
ark/ops/ops_copy.cc	92.30% <ø> (ø)
ark/ops/ops_embedding.cc	94.73% <ø> (ø)
ark/ops/ops_im2col.cc	81.53% <ø> (ø)
ark/ops/ops_layernorm.cc	87.87% <ø> (ø)
... and 19 more