Augment IP_DETAILS, IP_ADDRESS_DETAILS with a few context fields.

Augment IP_DETAILS, IP_ADDRESS_DETAILS with a few context fields.

When handling the IP_DETAILS and IP_ADDRESS_DETAILS replies,
it is almost certainly going to require having both the is_ipv6
and sw_if_index context to handle them properly.  Placing these
values in an essentially global location as the current VAT does
isn't thread-safe.  Fruthermore, rather than forcing every
API user to hoop-jump to establish these context values, simply
provide them in their DETAILS reply messages.

Change-Id: I6a9e0cb16ecdbf87fca8fc5c7663e98d3a53c26c
Signed-off-by: Jon Loeliger <jdl@netgate.com>