[lib] introduce DispatchMetadata for Inbound and Outbound actions
Summary:
ENG-8423.
This improves types and naming to reflect rest of the codebase.
SCHEDULE_P2P_MESSAGES is no longer needed, P2P messages are now part of PROCESS_DM_OPS.
Depends on D13151
Test Plan:
Flow
Note: This stack is tested end-to-end according to the process described here.
Reviewers: tomek, inka
Reviewed By: tomek
Subscribers: ashoat
Differential Revision: https://phab.comm.dev/D13152