Enrolment Button on Session Card / Session Details

[ilirhushi]

Is your feature request related to a problem? Please describe.
Each such component should conditionally show enrolment button or already enrolled indication

Describe the solution you'd like

• to get all the current sessions where the uid is of the current user
• use a service to lookup against

Describe alternatives you've considered

• not iterate data query because it’s expensive

Additional context

• service should be cleaned up onDestroy