[xla:gpu] NFC: Simplify AddressComputationThunk by replacing llvm::zip with struct
[xla:gpu] NFC: Simplify AddressComputationThunk by replacing llvm::zip with struct

Remove accidental copies of various temporaries by packing all arguments into struct and iterating over a single vector.

Also fix a bug with accessing offsets buffers stored on host, original [arg_idx + offset] offset computation is simply incorrect.
