More CTS tests for ECDSA and RSA signatures.

This makes Android Keystore Signature tests run for keys of all
typical sizes, instead of just one RSA and one EC key.

Known-Answer Tests still use only one RSA and one EC key for now.

Bug: 21936191
Bug: 22492259
Change-Id: I857e82e20aa5ef35ea9b2bdd7b745a7403e0812c
25 files changed