tests_reg: Add test for refused connection in IPC-NS

Add tfm_ipc_test_1018 test case to check the correct PSA_ERROR
returned value from a RoT which refuses a connection.

Signed-off-by: Nicola Mazzucato <nicola.mazzucato@arm.com>
Change-Id: If38dfb05aaa4642abe36a8e14f1b4009779ff1da
3 files changed