chat groups: establish connection between host and invitee members (#77)

* create group after invitation

* add group invitation to db, show sent and received group invitations

* test creating group and sending invitation

* establish group connections (WIP)

* connect user to the inviter, notification, member classification

src/Simplex/Chat/Controller.hs

@@ -40,7 +40,14 @@ data ChatError
   | ChatErrorStore StoreError
   deriving (Show, Exception)
 
-data ChatErrorType = CEGroupRole | CEGroupDuplicateMember deriving (Show, Exception)
+data ChatErrorType
+  = CEGroupRole
+  | CEGroupDuplicateMember ContactName
+  | CEGroupDuplicateMemberId
+  | CEGroupNotJoined GroupName
+  | CEGroupMemberNotReady
+  | CEGroupInternal String
+  deriving (Show, Exception)
 
 type ChatMonad m = (MonadUnliftIO m, MonadReader ChatController m, MonadError ChatError m)