* Timestamps refactored to int64 (nanoseconds resolution). Related to https://github.com/status-im/nim-waku/issues/834
* Updated times to Timestamp type
* Refactored timestamps
* Made spec consistent with timestamp refactoring
* Fixed misunderstanding on proto3 types
* Fixed timestamps to sint64
* Fixed correct time to pb2 timestamps and Store protocol version changed to beta4
* Revert changes (not needed for now)
* Revert changes
We'll change to sint64 when we'll refactor chat2 to use Timestamp type for timestamps