xla

e42fffa0 - [SPMD][Virtual Device]All tensors should be in SPMD:0 C++ device (#5284)

[SPMD][Virtual Device]All tensors should be in SPMD:0 C++ device (#5284) * Move all tensors to SPMD:0 C++ device under spmd context * fix load shards * fix test_mark_sharding_2d by not creating placeholder for virtual device * fix the waitdeviceop for spmd case * Fix test_shard_hashing * fix spmd device casting issue * remove hacks in test_xla_virtual_device.py * add test for new virtual device usage * fix review comments * fix IsTpuDevice * linter