Improve users/groups graph api endpoint

[AlexAndBear]

To build up a performant user management with user and group assignments it is necessary to improve the graph API:

1. /graph/v1.0/users/ endpoint should include a field where assigned groups are listed (maybe $expand is necessary)
2. /graph/v1.0/users/{id}/ endpoint should include a field where assigned groups are listed (maybe $expand is necessary)
3. /graph/v1.0/groups/ endpoint should include a field where assigned users are listed (maybe $expand is necessary)
4. /graph/v1.0/groups/{id}/ endpoint should include a field where users are listed (maybe $expand is necessary)
5. We need an endpoint to set the user's group with one request instead of adding and deleting group relations by single requests
6. We need an endpoint to set the group's users with one request instead of adding and deleting user relations by single requests

5 & 6 extracted into it's own issue

[AlexAndBear]

FYI @butonic

Please NOTE: The API specification claims that point 1-4 is already possible, which is not the case. We SHOULD really not add things to our API specification which are not included yet, the specification should represent the current state AND NOT contain future improvements

[micbar]

let us treat it as a bug and fix it.

[dragonchaser]

@janackermann && @micbar 5 & 6 are not part of the spec (see https://docs.microsoft.com/en-us/graph/api/resources/user?view=graph-rest-1.0#relationships) do we want to implement outside of the spec?

[fschade]

i would say skip 5 & 6 for now, i'm really not happy to work around the spec atm.

[kulmann]

I agree, 5 & 6 can be mitigated client side for the moment. 1-4 would be good to have.

[fschade]

@dragonchaser, point 5 & 6 is extracted into a separate issue to keep this rolling.

#3963