CMake: unit-tests: Move mbed-headers-rtos to the rtos directory

Move the header-only mbed-headers-rtos library the unit test stubs
depend on into the rtos component directory. This makes the rtos
stubs more self-contained and improves the composition of the library.

Author: rajkan01

UNITTESTS/stubs/CMakeLists.txt

@@ -9,7 +9,6 @@ add_library(mbed-headers-connectivity INTERFACE)
 add_library(mbed-headers-storage INTERFACE)
 add_library(mbed-headers-hal INTERFACE)
 add_library(mbed-headers-events INTERFACE)
-add_library(mbed-headers-rtos INTERFACE)
 
 target_link_libraries(mbed-headers
     INTERFACE
@@ -101,12 +100,6 @@ target_include_directories(mbed-headers-hal
         ${mbed-os_SOURCE_DIR}/hal/include
 )
 
-target_include_directories(mbed-headers-rtos
-    INTERFACE
-        ${mbed-os_SOURCE_DIR}/rtos/include
-        ${mbed-os_SOURCE_DIR}/rtos/include/rtos
-)
-
 target_include_directories(mbed-headers
     INTERFACE
         ${mbed-os_SOURCE_DIR}/features

rtos/tests/UNITTESTS/doubles/CMakeLists.txt

@@ -1,6 +1,14 @@
 # Copyright (c) 2021 ARM Limited. All rights reserved.
 # SPDX-License-Identifier: Apache-2.0
 
+add_library(mbed-headers-rtos INTERFACE)
+
+target_include_directories(mbed-headers-rtos
+    INTERFACE
+        ${mbed-os_SOURCE_DIR}/rtos/include
+        ${mbed-os_SOURCE_DIR}/rtos/include/rtos
+)
+
 add_library(mbed-stubs-rtos-headers INTERFACE)
 
 target_include_directories(mbed-stubs-rtos-headers