Add ConsensusMessageChunkInfo data to the topics REST API response

[gregscullard]

Problem
Large HCS messages may be sent in several chunks to Hedera, the protobuf message may optionally include information such as the total number of chunks and the current chunk number in a HCS Message.

This information is not relayed by the REST api when present, making it impossible to reliably reassemble large messages by clients.

reference: https://github.com/hashgraph/hedera-protobufs/blob/main/services/ConsensusSubmitMessage.proto

Solution
If present in the transaction's protobuf, include the ConsensusMessageChunkInfo data along with the message and its attributes.

Alternatives
A client may include a size indicator at the start of every large message they send, look for this information on messages returned by the REST api and reconstitute messages that way, however this is re-inventing the wheel and could go wrong if several large consensus messages are sent at the same time by different clients to the same topic.