Test: Add fetch eRPC remote library

Add fetch eRPC remote library.
eRPC is integrated with tf-m tests.

Signed-off-by: Summer Qin <summer.qin@arm.com>
Change-Id: Iad79d5169e3345b52deb79ea2855c29453297db2
diff --git a/CMakeLists.txt b/CMakeLists.txt
index ecfd432..0f09d25 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1,5 +1,5 @@
 #-------------------------------------------------------------------------------
-# Copyright (c) 2021-2022, Arm Limited. All rights reserved.
+# Copyright (c) 2021-2023, Arm Limited. All rights reserved.
 #
 # SPDX-License-Identifier: BSD-3-Clause
 #
@@ -7,6 +7,8 @@
 
 add_subdirectory(log)
 
+add_subdirectory(lib/ext)
+
 if(NS)
     add_subdirectory(app)
 endif()