Add t_cose library as external component

To support signing of cbor encoded attestation reports, the
t_cose library has been added as an external component.  To
verify the external component, it has been included in
the component-test build.

Signed-off-by: Julian Hall <julian.hall@arm.com>
Signed-off-by: Gyorgy Szing <gyorgy.szing@arm.com>
Change-Id: I1cff695b1efd01090be1e51b769f7615703d5184
6 files changed