LWIP::get_ip_addr: Prefer IPv4 over IPv6 link local addresses ...

When IPv6 is prefered it will choose a link local address on a network
that lacks IPv6 over a working IPv4 network, breaking networking.
Change this behaviour to prefer a link local address only as a last
resort.

This also changes LWIP::get_ipv6_addr to not return link local
addresses. Use get_ipv6_link_local_addr instead for this.

Code improvements for the unresolved comments ...

This patch contains improvements mentioned in the unresolved PR
comments:
- function names were changed from socket_sendmsg/socket_recvmsg to
  socket_sendto_control/socket_recvfrom_control.
- default implementation of this functions was provided in the
  NetworkStack class.
- MsgHeaderIterator accesses elements on the aligned addresses.

New feature: send/recv message implementation added to network stack

Add LWIP Broadcast option for UDP socket.

Merge pull request #13671 from balajicyp/topic/setsockopt_ip_tos ...

Add an socket option to set type of service to set specific precedence for QoS

Remove erroneous character from SPDX identifer ...

Erroneous '/' was appended to start of comment. This was causing CMake
warning during complition. Removes character from affected files.

Add SPDX license identifier to Arm files ...

Add license identifier to files which Arm owns the copyright to,
and contain either BSD-3 or Apache-2.0 licenses. This is to address
license errors raised by scancode analysis.

Add nsapi types for IP TOS and fix opt length check

set ip type of service to set specific precedence for QoS

set ip type of service to set specific precedence for QoS

Move lwipstack ...

- Public headers moved into mbed-os/connectivity/lwipstack/include/lwipstack folder
- Source moved into mbed-os/connectivity/lwipstack/source folder
- Internal lwip and lwip-sys libraries moved to source folder