Expose more groups features in signalR

[NaNgets]

Is there an existing issue for this?

• I have searched the existing issues

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

No response

Describe the solution you'd like

The IGroupManager should expose more methods for better utilizing the groups and connections. Subsequently, the HubLifetimeManager.

1. It should allow to get the groups by a connection (something like GetGroupsByConnection).
2. It should allow to get the connections by a group (something like GetConnectionsByGroup).

These will allow better control over the connection and its groups, for instance if we have added a connection to a group and later we want to clear all the groups - this will allow us to get the list of the groups and remove the connection from them.

Additional context

No response

[NaNgets]

If I will make a pull request for it, will it be considered?

There are no responses so I don't want to work and be overlooked.