Allow to pass did when creating invitation

[TimoGlastra]

When creating an invitation we currently generate a peer did doc by default. In addition it would be nice if we can add an optional did property when creating an out of band invitation. The did can be created beforehand using the did registrar (#953). It is the responsibility of the user to make sure the did contains did comm services (we could add a check).

This would allow to use public dids for out of band invitations.

Notes:

• When a public did is used to create an invitation, we should somehow register this key in the multi tenant module for routing. We should somehow integrate this with the RoutingCreatedEvent.