Add support for JSON object and array values in map entries

[lawrence-forooghian]

• https://ably.atlassian.net/wiki/spaces/LOB/pages/4203380843/LODR-040+ObjectData+JSON+encoding+of+object+and+array+values
• [PUB-1667] Add support for encoding/decoding JSON objects for LiveMap values ably-js#2052

To be done:

• update public API
• update wire protocol for JSON map values

The wire changes are not specified yet but the write API of ably/specification#353 expects us to accept JSON objects and arrays.

┆Issue is synchronized with this Jira Task by Unito