Add new api to open all devices in cluster

[ubcheema]

Need a new api to open all devices in the cluster with a single call.

for mmio_device in mmio devices:
  open mmio_device
  for tunnel_count in mmio_device:
    for remote_chips in mmio_device.tunnel_number
      open remote device

[ubcheema]

std::map<chip_id_t, Device *> CreateDevices in tt_metal.cpp is providing the ability to create all devices behind a mmio device.
I believe we can use that, so we don't need to do any new api for this issue at this point.