Enable meeting organisers to state who of the registered attendees actually attend

Is your feature request related to a problem? Please describe.
As a meeting organizer, it's important that in my past events I can distinguish between who said they would attend (registered) and who actually participated (attendees). Currently this is a somewhat manual/non existent process, you have to write the organizations who attended in the box when closing the meeting but there's nothing about the members who registered to the event with their Decidim account and whether they did or did not attend/participate. We get around this by manually writing in the minutes on the connected Etherpad the attendees.

The context is for us, as an open source project, we log those attendances as a contribution. Therefore we'd like to be able to know, via the code/API, who actually attends the meeting.

Furthermore, it means that as an organization, if you're using the number of registered participants to proxy the number of attendees, the number could be grossly misleading.

Describe the solution you'd like
I would like to be able to:

1. When closing a meeting, select from the Decidim members who registered, those who actually attended/participated in the meeting (or perhaps you could suggest this from logged in users who clicked the link to join the call and give the option to add/remove as appropriate?)

2. Add users who did not register for the meeting in advance by searching and selecting their Decidim profile,

3. Have Decidim then know from their profile, what their organization is, thereby making the manual filling of the organization box on minutes defunct (perhaps this could be added as a custom profile field?),

4. Have Decidim count the number of people attending and an option to use this for the number of contributions field.

Describe alternatives you've considered
Currently I have to manually review all meetings at the end of the month to grab who attended the meeting by manually reading the minutes, then I have to manually add contributors in our CRM. This takes me at least an hour every month.

Additional context
I think this would be a helpful feature in any communities where you need to be able to demonstrate actual engagement with events/meetings, not just people signing up to attend. It might be a bit unwieldy with larger meeting attendances so due consideration would need to be given for the UX/UI side of it.

Does this issue could impact on users private data?
It would show (if you wanted to) who actually attended v those who registered in the front-end. There should be an option to not be shown in attendees like there is to not be shown in registrations.

Funded by
This isn't currently funded.