[mlir][nvgpu] Add address space attribute converter in nvgpu-to-nvvm pass (#74075)

GPU dialect has `#gpu.address_space<workgroup>` for shared memory of
NVGPU (address space =3). Howeverm when IR combine NVGPU and GPU
dialect, `nvgpu-to-nvvm` pass fails due to missing attribute conversion.

This PR adds `populateGpuMemorySpaceAttributeConversions` to
nvgou-to-nvvm lowering, so we can use `#gpu.address_space<workgroup>`
`nvgpu-to-nvvm` pass