The Windows Bluetooth stack uses private IOCTLs in order to set the [discoverability](https://learn.microsoft.com/en-us/windows/win32/api/bluetoothapis/nf-bluetoo...) and [connectability](https://learn.microsoft.com/en-us/windows/win32/api/bluetoothapis/nf-bluetoo...) status of a local radio, and to start/stop the device inquiry procedure. This MR introduces 3 wine-specific IOCTL codes for the same purposes, as most applications seem to the Win32 API itself for these operations:
* IOCTL_WINBTH_RADIO_SET_FLAG * IOCTL_WINEBTH_RADIO_START_DISCOVERY * IOCTL_WINEBTH_RADIO_STOP_DISCOVERY
-- v12: bluetoothapis: Implement BluetoothEnableDiscovery. bluetoothapis/tests: Add tests for BluetoothEnableDiscovery. bluetoothapis: Add stub for BluetoothEnableDiscovery. bluetoothapis: Implement BluetoothEnableIncomingConnections. bluetoothapis/tests: Add tests for BluetoothEnableIncomingConnections. bluetoothapis: Add stub for BluetoothEnableIncomingConnections. winebth.sys: Call bluez_watcher_close as part of bluetooth_shutdown.