Add cert_chain output argument to KeyFactory.

KeyMint needs to return certificate chains from GenerateKey and
ImportKey.  This CL adds the output argument to the right methods, but
does not implement the certificate generation.

Test: keymaster_tests
Bug: 171846199
Change-Id: Ia914f5766c0317cd75ef8f77d7f5aa7b95c2a05b
15 files changed