Implement the SecureBox crypto functions

SecureBox provides a set of simple interfaces for performing encryptions
and decryptions, by using a public key owned by the recipient and/or a
secret shared by the sender and the recipient.

Bug: 69056040
Change-Id: I45abd7ec5d6f1fd6f6e3ad6d84352958dd838dd7
Fixes: 69056040
Test: adb shell am instrument -w -e package com.android.server.locksettings.recoverablekeystore com.android.frameworks.servicestests/android.support.test.runner.AndroidJUnitRunner