Refactor sts-crypto-utils and make them shared with Datasafe crypto utils

Both sts-crypto-utils and https://github.com/adorsys/datasafe/tree/develop/datasafe-encryption/datasafe-encryption-impl
share lots of common operations - reading keystore, creating keys, etc. We should extract them into common repository that should have decent coverage and reduced boilerplate code (we can start as maven artifact that resides in Datasafe)