Make a sequence diagram for the interaction between user, perun node, and the sdk.

#### Motivation / Context

To get a high level view of the interaction between user, perun node and the sdk.

#### Description

Make a seqeunce diagram for the interaction between user, perun node and the sdk. The diagram should consists of separate blocks each corresponding to different stages of a state channel life cycle: Opening, Using and Settling (Collaboratively and Non Collaboratively).

Each interaction should either be initiated by the user or the sdk.
1. On any incoming event from the sdk, node should inform the user of this event (if relevant to the user).
2. Any interaction initiated by the user should end in the node sending a response to the user.

##### Relates to

#### Testing

#### Thread Safety