[keyserver][lib][native] Add lastCommunicatedPlatformDetails to keyserverStore

Summary:
issue: https://linear.app/comm/issue/ENG-4462/refactor-lastcommunicatedplatformdetails-field
The first step is to add lastCommunicatedPlatformDetails to the keyserverStore.

Test Plan: ran yarn flow-all. Checked that there are no validation errors.

Reviewers: michal, kamil

Reviewed By: michal

Subscribers: ashoat, tomek

Differential Revision: https://phab.comm.dev/D9077