Refactor: scheduler: Change args to pe__unpack_dataset_nvpairs.
    
    It should now take a pe_rule_eval_data_t instead of various separate
    arguments.  This will allow passing further data that needs to be tested
    against in the future (such as rsc_defaults and op_defaults).  It's also
    convenient to make versions of pe_unpack_nvpairs and
    pe_unpack_versioned_attributes that take the same arguments.
    
    Then, adapt callers of pe__unpack_dataset_nvpairs to pass the new
    argument.