* added csrc/stack.cc * stack: added checks * added copyright info * passed cpp style checks * formatted code * added some support for streaming conformer model support (not verified) * code lint * made more progress with streaming conformer support (not working yet) * passed style check * changes as suggested by @csukuangfj * added some debug info * fixed style check * Use Cat to replace Stack * remove debug statements --------- Co-authored-by: Jingzhao Ou (jou2019) <jou2019@cisco.com> Co-authored-by: Fangjun Kuang <csukuangfj@gmail.com>