This comment adds (1) basic support for AF_BLUETOOTH sockets.  The logic compiles but is still incomplete.  Support for Bluetooth is general is still dependent on CONFIG_EXPERMIMENTAL because it is not yet ready for used.

Squashed commit of the following:

    wireless/bluetooth:  Some small changes that gets to a clean compile by just eliminating some incorrect implementations (still with a lot of warnings.  The logic is still incomplete but now not so lethal.
    wireless/bluetooth:  Restructuring:  Connection interfaces should internal to wireless/bluetooth.  include/nuttx/wireless/bt_conn.h removed and merged with wireless/bluetooth/bt_conn.h.  Several fix to get closer to bt_netdev.c compiling.  Need to design some not interfaces and use some existing interfaces to send and receiv packets.
    wireless/bluetooth: Some organization with some network device compile errors fixed.  Still not even close to compiling.
    net/bluetooth:  Fix numerous compile issues; Still open design issues with regard to the interface with the Bluetooth stack.
    wireless/bluetooth:  Create bt_netdev.c with a crude copy of mac802154_netdev.c.  Does not not even compile yet.
    include/nuttx/net:  Add bluetooth.h.  Content is not yet correct.
    net/netpackets:  Add bluetooth.h.  Update net/bluetooth to use new socket address definition.
    net/bluetooth:  Some fixes for initial build.
    net/bluetooth:  Add initial support for Bluetooth sockets.  The initial cut is just the a clone of the IEEE 802.15.4 socket support with name changes.
    net/ieee802154:  Fix some typos noted when cloning to create net/bluetooth.