Move conscrypt out libjavacore and split tests

To make the situation with testing a little better and enable building
core libraries totally independent of conscrypt, move the native
registration to a JNI_OnLoad scheme. Also, since we want to separate the
testing, make conscrypt build its own tests library.

Change-Id: I9f2831839059c1c012ec7bdeab2f90b4e2f44bfd
5 files changed