Development of a Spin-Exchange Optical Pumping-Based Polarized 3He System at the China Spallation Neutron Source (CSNS)Supported by the National Key Research and Development Program of China (Grant No. 2020YFA0406000), the National Natural Science Foundation of China (Grant No. 11875265), the Scientific Instrument Developing Project of the Chinese Academy of Sciences (Grant No. 284(2018)), Guangdong Basic and Applied Basic Research Foundation (Grant No. 2019B1515120079) and Dongguan Introduction Program of Leading Innovative and Entrepreneurial Talents (Grant No. 20191122). (October 2021)