Add top chirps and paging for chirps on Go

[osm-alt]

Description

The paged_catchup message and the top chirps functionality in the catchup message that are described in protocol.md have not been added to the Go subsystem yet. Please note that add chirp message and delete chirp messages should also be added to a universal chirp channel ("/root/lao_id/social/chirps"). This is mentioned in docs/messageData.md

These messages have been implemented on Scala.

Front-ends:

• [ ] Fe1-Web (please include browser's names & version)
• [ ] Fe2-Android (please specify if phone or emulation, and Android version)
• [x] Not applicable

Back-ends:

• [x] Be1-Go
• [ ] Be2-Scala
• [ ] Not applicable