Exchange cloud IDs between remote users

Is your feature request related to a problem? Please describe.

This feature addresses the somewhat cumbersome process of retrieving the cloud ID of a remote user you want to federatively share with.
This feature will enable the user to send an invitation to a remote user to exchange cloud IDs. It basically extends the contacts app with the option to exchange with a remote user name, email and cloud ID resulting in the creation of contact info on each other's system (sort of like exchanging a contact card, including cloud ID). From then on both users can share with each other as easy as with local users.
The features relies on an implementation of the Invitation Workflow (see https://github.com/sara-nl/nc-collaboration).

Describe the solution you'd like

Goals:

• in contact form in the cloud ID property section there should be a button that opens cloud ID exchange invitation popup
  . results in a new contact (name, email, cloud ID)
  . should also work with an existing remote contact
• cloud ID exchange invites awaiting acceptance should be visible from within the cloud ID property field of a contact
  . message at sender end of invite: '... waiting for cloud ID exchange response'; a button for revoking should be present
  . message at receiver end of invite: '.. awaiting your approval for cloud ID exchange'; a button for accepting/declining should be present
• make availability of this feature configurable
  . the dependencies (Collaboration app) should be automatically detected

Some mock-up screenshots of what we're after:

Additional context

• OCM /invite-accepted endpoint specification (invitation workflow): https://cs3org.github.io/OCM-API/docs.html?branch=v1.1.0&repo=OCM-API&user=cs3org#/paths/~1invite-accepted/post
• Collaboration app for Nextcloud (implements Invitation Workflow): https://github.com/sara-nl/nc-collaboration
• Presentation of the Invitation Workflow: https://indico.cern.ch/event/1467643/contributions/6321230/