Slack Protostub: support presence / status interworking

[pchainho]

https://api.slack.com/docs/presence-and-status

[pchainho]

Some more details:

• When the Slack channel is created checks if it already exists. If yes, retrieves existing members and asks the GRoup Chat reporter to add them as participants to the Group Chat:
  • invokes execute('addUser', [users,domains]) Group Chat DataObject Observer with
  • Group Chat Manager onExecute() handler adds the new the participant to the Group Chat
• the slack protostub is listening for new members performs the previous step
• one User Availability Reporter (UAR) for each participant on Slack side (that is not the reTHINK user) that translates Slack presence status change and writes on UAR data object
• one User Availability Observer (UAO) that translates changes on the UAO data object to publish slack status change

[pchainho]

DataObjectObserver.execute() and ChatController ready to handle onExecute():

• reTHINK-project/dev-hyperty@4704724

GroupChatManager demo updated with this new feature: Now observers can also add new participants