Add SerializableResource and GetSerializedResouceOp. This is needed by:

1. the new calibration design. The current int8 calibration workflow depends on
   a global resouce manager singleton TRTResourceManager (in
   resources/trt_resource_manager.h). This has been:
   - violating the resource manager design: resource manager should be
     per-device
   - pollutes the BUILD dependencies, and makes the kernel implementation not
     able to be used in other language bindings (Issue #23853)
2. the custom backend offline mode, where we'll do the conversion during
   execution and provide an offline tool to get the serizlied engine

PiperOrigin-RevId: 229654702