Expose more groups features in signalR

### Is there an existing issue for this?

- [X] 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](https://github.com/dotnet/aspnetcore/blob/main/src/SignalR/server/Core/src/IGroupManager.cs) should expose more methods for better utilizing the groups and connections. Subsequently, the [HubLifetimeManager](https://github.com/dotnet/aspnetcore/blob/main/src/SignalR/server/Core/src/HubLifetimeManager.cs).

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_