message: Create core package.
diff: @@ -5,12 +5,12 @@ from __future__ import google_type_annotations
  from __future__ import print_function
  from google3.third_party.tink.python import aead
  +from google3.third_party.tink.python import core
  from google3.third_party.tink.python import daead
  from google3.third_party.tink.python import hybrid
  -from google3.third_party.tink.python import key_manager
  from google3.third_party.tink.python import mac
  from google3.third_party.tink.python import signature
  -from google3.third_party.tink.python import tink_config
  +from google3.third_party.tink.python.core import tink_config
  Aead = aead.Aead
  @@ -21,7 +21,24 @@ Mac = mac.Mac
  PublicKeySign = signature.PublicKeySign
  PublicKeyVerify = signature.PublicKeyVerify
  -KeyManager = key_manager.KeyManager
  -PrivateKeyManager = key_manager.PrivateKeyManager
  +KeyManager = core.KeyManager
  +PrivateKeyManager = core.PrivateKeyManager
  -del key_manager
  +Registry = core.Registry
  +
  +new_keyset_handle = core.new_keyset_handle
  +read_keyset_handle = core.read
  +KeysetHandle = core.KeysetHandle
  +
  +
  +KeysetReader = core.KeysetReader
  +JsonKeysetReader = core.JsonKeysetReader
  +BinaryKeysetReader = core.BinaryKeysetReader
  +
  +KeysetWriter = core.KeysetWriter
  +JsonKeysetWriter = core.JsonKeysetWriter
  +BinaryKeysetWriter = core.BinaryKeysetWriter
  +
  +new_primitive_set = core.new_primitive_set
  +
  +TinkError = core.TinkError
  