group commands (remove member, leave group, delete group) (#87)

* remove group member

* leave group, fix remove member, tests for leave group/remove member

* delete group with test

* prevent contact deletion error when it is a group member

* support inviting the group member who left or was removed

* use small retry interval in the tests

* test multiline outputs

src/Simplex/Chat/Controller.hs

@@ -47,6 +47,8 @@ data ChatErrorType
   | CEGroupDuplicateMemberId
   | CEGroupNotJoined GroupName
   | CEGroupMemberNotActive
+  | CEGroupMemberUserRemoved
+  | CEGroupMemberNotFound ContactName
   | CEGroupInternal String
   deriving (Show, Exception)