Use EVP_PKEY_get1_RSA to get RSA reference

EVP_PKEY structures could be of any number of key types. Switch to
EVP_PKEY_get1_RSA because that will check that the key type before it
tries to pull out the RSA pointer. This prevents crashes when the key
type is not actually RSA.

Bug: 10647482
Change-Id: I6848db52b04ed11331138ac00f0796574a87fa6a
Use canonical UniquePtr.h header

Change-Id: Ic8f3263ad83c3cd3bf0f5a9c847ee26910afb616