RootCanal: Support LE 4.1 advertising

Bug: 139080884
Test: Start and stop advertising with root_canal desktop

Window #1:
$ ./root_canal

Window #2:
$ python test_channel.py 6401
 $ add_device_to_phy 1 2
 $ add sniffer 00:00:00:00:00:00
 $ add_device_to_phy 2 2

Window #3:
  # Connect a new HCI device
$ python3 simple_stack.py 6402
  # Set the Random address to 1 2 3 4 5 6
 $ send 01 05 20 06 01 02 03 04 05 06
  # Enable BLE advertising
 $ send 01 0A 20 01 01
  # Disable BLE advertising
 $ send 01 0A 20 01 00 
  # Configure advertising (interval 0x06-0x50, random address, peer 01:02:03:04:05:06)
 $ send 01 06 20 0F 06 00 50 00 00 01 00 01 02 03 04 05 06 07 00

Change-Id: I5922d88792803847822e5d56aa57a49140c8363f