Keystore 2.0 legacy wrapper: Fix best padding candidate lookup.

Also add signature padding only if algorithm RSA was selected and add
Digest::None as viably selectable digest.

Test: atest android.keystore.cts.KeyPairGeneratorTest#testGenerate_RSA_ModernSpec_UsableForTLSPeerAuth
Change-Id: I917afe345c96f4f13fe7afc9430e621b3ba567bf
1 file changed