Signing on behalf of a user delegated organization

[HauklandJ]

Description

An organization may be delegated rights to sign for an instance of an application. We need to know if the current user is able to sign on behalf of one or more of the organisationSignees.

Additional Information

We need an endpoint in SigningController which uses the current users userId and a list of organisation party ids. We will then call the GetRoles endpoint for each of the organisation signee party ids to get the decision point roles for the user in the given organisation.
We should curate the roles for signing relevant roles and simply return a list of organisation number party ids for which the user can sign