app: Add a static library for the PSA tests

This allows external build systems (like Zephyr) to easily pick up and
build the PSA tests in their own context.

Signed-off-by: Øyvind Rønningstad <oyvind.ronningstad@nordicsemi.no>
Change-Id: Ic376c8943f53dd729665e99148f8de55e2d0c061
1 file changed