Example Linalg3: support Load/Store conversion from Linalg to LLVM IR dialect

    Load and Store Linalg operations are converter to their LLVM IR counterparts
    preceded by a sequence of operations that recover the effective address of the
    accessed element.  The address is computed given the subscripts and the view
    descriptor as

        base_pointer + base_offset + SUM_i subscript_i * stride_i.

    Manual testing shows that the resulting LLVM IR for the matrix multiplication
    example can be compiled and executed, producing correct results.

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PiperOrigin-RevId: 241889003