[lib] Create empty specs for update types
Summary:
Create an object with empty specs for each update type.
https://linear.app/comm/issue/ENG-4241/handle-processupdatesactiontype-as-a-part-of-a-spec
Test Plan: Flow
Reviewers: kamil, bartek, inka
Reviewed By: kamil
Subscribers: ashoat, michal
Differential Revision: https://phab.comm.dev/D9244