Refactor emiter (#1879) (#1944)

* split big Emitter to submodules.

* fix all deprecated warning.

Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>
(cherry picked from commit 92af63c5

)

Co-authored-by: Jiuyang Liu <liu@jiuyang.me>