HIP-874: Get topic REST Java implementation

[Nana-EC]

Problem Currently /api/v1/topics/:id/messages exist to retrieve messages of a topic However, there's no API to get the info of a single topic similar to /transactions:id, /accounts/:id

Solution Add an /api/v1/topics/:id endpoint to expose a single topics info Details could include things like memo, latest sequence number/ # of messages

Alternatives

• Explore the extent of info to be exposed in relation to https://docs.hedera.com/guides/docs/hedera-api/consensus-service/consensustopicinfo and what customers need when querying topics

Additional Context See #773 as there will be overlap