Use JCA names for block modes, paddings, and digests.

This replaces int-based enums from KeyStoreKeyConstraints with
String values commonly used in JCA API.

As part of under the hood refactoring:
* KeyStoreKeyCharacteristics and KeyStoreKeyConstraints have been
  merged into KeyStoreKeyProperties.
* KeymasterUtils methods operating on KeymasterArguments and
  KeymasterCharacteristics have been moved to their respective
  classes.

Bug: 18088752
Change-Id: I9c8b984cb3c28184adb617e34d87f2837bd1d3a1