[lib] rename MessageToDevice from SQLite to OutboundP2PMessage

Summary:
MessageToDevice and ClientMessageToDevice are used in different context in codebase which makes it hard to understand and confusing, renaming to OutboundP2PMessage.

Depends on D12046

Test Plan: Flow & tests

Reviewers: tomek, bartek

Reviewed By: bartek

Subscribers: ashoat

Differential Revision: https://phab.comm.dev/D12047