[lib] refactor createOlmSessionWithPeer -> createOlmSessionsWithUser in PeerOlmSessionCreatorContextType

Summary:
ENG-9106.

Update context to support multiple devices.

Callsites are updated later in the stack.

Depends on D13371.

Test Plan: Tested in D13376

Reviewers: bartek, tomek, marcin

Reviewed By: bartek, tomek, marcin

Subscribers: ashoat

Differential Revision: https://phab.comm.dev/D13372