Build: Convert app directory to modern cmake

update app cmake files. Update header includes where include paths have
changed. Add support for secure test only enablement.

WARNING: This change will not build in isolation, it requires _all_
other cmake changes to successfully build. It is split out only for ease
of understanding.

Signed-off-by: Raef Coles <raef.coles@arm.com>
Change-Id: I3e8eb83c13b5e4dbb428615ba83567f14000285b
diff --git a/app/tfm_integ_test.h b/app/tfm_integ_test.h
index 93c46a5..f65f4f1 100644
--- a/app/tfm_integ_test.h
+++ b/app/tfm_integ_test.h
@@ -26,14 +26,14 @@
  */
 #define UNUSED_VARIABLE(X) ((void)(X))
 
-#ifdef TEST_FRAMEWORK_NS
+#if defined(TEST_FRAMEWORK_NS) || defined(TEST_FRAMEWORK_S)
 /**
  * \brief Main test application for the RTX-TFM core
  *        integration tests
  *
  */
 void test_app(void *argument);
-#endif /* TEST_FRAMEWORK_NS */
+#endif /* TEST_FRAMEWORK_NS || TEST_FRAMEWORK_S */
 
 #ifdef __cplusplus
 }