Following https://abseil.io/tips/122 to make tests easier to understand and adds a bit of flexibility to create sockets with custom parameters. This also simplifies handover tests. Additionally, AdvanceTime will now also run timers, as that was easily forgotten previously. Bug: None Change-Id: Ieb5eece7aca51c98a7634ed1c61646383ad1712d Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/253782 Reviewed-by: Sergey Sukhanov <sergeysu@webrtc.org> Commit-Queue: Victor Boivie <boivie@webrtc.org> Cr-Commit-Position: refs/heads/main@{#36141}