* feat(plugins): add chat server command and chat message type `plugin`
This commit adds the required code for the plugins SDK's chat server
command `CHAT_SEND_MESSAGE`, which allows plugins to send chat
messages. Messages sent by plugins are identified by the message
type `plugin` and belong to the user (senderID) of the client that
sent it. Plugin messages are not displayed by the client itself because
these messages are meant to be custom-rendered by plugins, typically by
the plugin that sent them.
* feat(plugins): add message metadata
Plugin name and plugin custom metadata are stored in message's metadata,
so plugins need it to identify messages when applying custom render.
* feat(chat): removes specific code for plugin messages
Removes specific akka messages, handlers and routes for plugin messages
and adds metadata parameter in `GroupChatMsgFromUser`.
* feat(chat): adds option parameter to mutation
Adds optional parameter `metadata` to the already existing mutation
`chatSendMessage` and use this mutation for plugin chat server command.
* feat(chat): rendering of plugin messages
This commit implements the correct rendering of plugin messages, which
is:
- Plugin messages with metadata attribute `custom` set to true are not
rendered by the client, and are meant to be custom-rendered by
plugins.
- Plugin messages with metadata attribute `custom` set to false are
rendered by the client as being sent by the user that triggered it.
* Update sdk version to v0.0.56
* update sdk version to v0.0.57
