[IOT-3259] Copy corresponding priv key
[IOT-3259] Copy corresponding priv key

Search for the corresponding private key among
the ASYMMETRIC_KEY type credentials and copy it
to the appropriate SIGNED_ASYMMETRIC_KEY type
credential

Change-Id: I7b2f595671261708dc0a0769cd8ccb72de0918be
Signed-off-by: Aleksey Volkov <a27d9cdf263d3bb0a7e1b2122425c0a535a3f64c@samsung.com>

iotivity/iotivity,iotivity/iotivity,rzr/iotivity,rzr/iotivity,iotivity/iotivity,rzr/iotivity,rzr/iotivity,iotivity/iotivity,iotivity/iotivity,rzr/iotivity,rzr/iotivity,iotivity/iotivity,iotivity/iotivity,rzr/iotivity,iotivity/iotivity