Specifying a precise topology

**What would you like to be added**: For measuring performance and debugging, we often need to specify a set topology (eg/ say I need 8 nodes, I want exactly 1 node in the first rack, 3 nodes on the second rack, and 4 nodes on the third rack). Unfortunately, this feature currently isn't supported by kueue: - `kueue.x-k8s.io/podset-slice-required-topology-constraints` can only be used to specify different topology layer, but not exact number of nodes on racks - `kueue.x-k8s.io/podset-slice-size=n` will guarantee a minimum of multiple of n nodes per rack, which means that you could end up with n, n\*2, n, n\*3 (because they are all multiples of n). Also, this doesn't give a way to specify an uneven number (eg/ I want 1, 3, 4 nodes on 3 racks respectively). **Why is this needed**: To rightsize the TAS required topology's podset slices, we want the precise number of nodes on different racks to see how it impacts performance. Also, we want to see how an uneven number of nodes on different racks when using TAS preferred topology impacts performance. In some cases, we were able to reproduce hanging given a specific number of nodes on different racks. **Completion requirements**: This enhancement requires the following artifacts: - [ ] Design doc - [ ] API change - [ ] Docs update The artifacts should be linked in subsequent comments.