[XLA] The HLO evaluator should preserve the layouts for instructions inside a

fusion.

When evaluating a fusion, the HLO evaluator makes a copy of the fusion and
resets the layout of each instruction in the copy to default layout before
evaluating the copy of the fusion. In doing that, it changes the layout of the
fusion intputs and outputs and causes incorrect results. This change fixes the
evaluator to not overwrite the layouts for the instructions inside a fusion.

Add test cases for fusion inputs, single output fusion and multiple output
fusion.

PiperOrigin-RevId: 227882142