Make the ObjectCode class lazy load modules

[ksimpson-work]

Currently this is executed at construction time:

if isinstance(module, str):
            # TODO: this option is only taken by the new library APIs, but we have
            # a bug that we can't easily support it just yet (NVIDIA/cuda-python#73).
            if jit_options is not None:
                raise ValueError
            module = module.encode()
            self._handle = handle_return(self._loader["file"](module))
        else:
            assert isinstance(module, bytes)
            if jit_options is None:
                jit_options = {}
            if backend == "new":
                args = (
                    module,
                    list(jit_options.keys()),
                    list(jit_options.values()),
                    len(jit_options),
                    # TODO: support library options
                    [],
                    [],
                    0,
                )
            else:  # "old" backend
                args = (module, len(jit_options), list(jit_options.keys()), list(jit_options.values()))
            self._handle = handle_return(self._loader["data"](*args))

This should happen in a lazy_load method. Certain uses of the ObjectCode object don't require the module to be loaded, such as linking ptx or ltoir code objects together.