[vote] Support multiple delegations

[ostcar]

@hjanott and @vkrasnovyd I try to apply this changes. But make generate-relational-schema returns with the message:

python -m src.generate_sql_schema
Models file /home/ossi/src/openslides-go/meta/dev/sql/schema_relational.sql created with 1 errors/warnings

    meeting_user/vote_delegations_from_ids: Type combination not implemented: nt:nr on field meeting_user/vote_delegations_from_ids

I am not sure how to solve this. I tried to add a reference to vote_delegations_from_ids, but this did not help.

Is this easy to fix? We would like to add the database change to the new vote service. But the client will not use it anyway. If it is not possible at the moment, then this is not a blocker, but something, we should be able to do in the near future.

[vkrasnovyd]

@ostcar you should remove 'reference' on both sides.

List of allowed relations in case you need to make further changes in the future: #539 (comment)

[ostcar]

@ostcar you should remove 'reference' on both sides.

List of allowed relations in case you need to make further changes in the future: #539 (comment)

Thank you. That helped. I still don't know when to add the reference and when not :)

Could you prepare a PR on the backend? For the moment, the client will never add more then one delegation. So it would be ok for the backend to reject multiple delegations. We want to add this change to the new vote service, that we don't need to change the database, if we add this feature later.

[ostcar]

os-go: OpenSlides/openslides-go#299
vote: OpenSlides/openslides-vote-service#566
autoupdate: OpenSlides/openslides-autoupdate-service#1450

@bastianjoel Do you need to update the projector-service?