BUG-6028: iterate over component types to instantiate union
This reworks union instantiation to be on par with
https://tools.ietf.org/html/rfc6020#section-9.12. We iterate
over individual members and attempt to run deserialization.
If it succeeds instantiate the union using cached constructor
specifying that member. This side-steps the need to go through
serialization.
Change-Id: Ieec37da37a05c2b2a2f432778232e136c903f654
Signed-off-by: Robert Varga <rovarga@cisco.com>
Signed-off-by: Isaku Yamahata <isaku.yamahata@intel.com>