Refactor Secure storage into frontend/backend

The secure storage service components are refactored as storage
frontends and backends.  Any frontend can be paired with any
backend.  Each backend implements a common interface.  This
allows new storage frontends and backends to be added more
easily and allows configurations such as proxies to be
created by simply pairing a service provider (frontend) with
a service client (backend).

Signed-off-by: Julian Hall <julian.hall@arm.com>
Change-Id: I5ef569ff3b61f64d6de69276d2b33e67a7ab0fa6
diff --git a/deployments/env-test/env_test.cmake b/deployments/env-test/env_test.cmake
index bf2b509..b809c1d 100644
--- a/deployments/env-test/env_test.cmake
+++ b/deployments/env-test/env_test.cmake
@@ -12,7 +12,7 @@
 #-------------------------------------------------------------------------------
 
 #-------------------------------------------------------------------------------
-#  Components that are common accross all deployments
+#  Components that are common across all deployments
 #
 #-------------------------------------------------------------------------------
 add_components(
@@ -32,7 +32,8 @@
 	"components/service/crypto/provider/mbedcrypto"
 	"components/service/crypto/provider/mbedcrypto/trng_adapter/platform"
 	"components/service/crypto/provider/mbedcrypto/trng_adapter/test"
-	"components/service/secure_storage/client/psa"
+	"components/service/secure_storage/frontend/psa/its"
+	"components/service/secure_storage/backend/secure_storage_client"
 	"protocols/rpc/common/packed-c"
 )