CMake: Refactor event unittest cmake

- Added CMake configuration file into events unittests

events/tests/UNITTESTS/CMakeLists.txt

@@ -0,0 +1,4 @@
+# Copyright (c) 2021 ARM Limited. All rights reserved.
+# SPDX-License-Identifier: Apache-2.0
+
+add_subdirectory(equeue)

events/tests/UNITTESTS/equeue/CMakeLists.txt

@@ -0,0 +1,34 @@
+# Copyright (c) 2021 ARM Limited. All rights reserved.
+# SPDX-License-Identifier: Apache-2.0
+
+set(TEST_NAME equeue-unittest)
+
+add_executable(${TEST_NAME})
+
+target_compile_definitions(${TEST_NAME} 
+    PRIVATE
+        EQUEUE_PLATFORM_POSIX
+)
+
+target_compile_options(${TEST_NAME}
+    PRIVATE
+        "-pthread"
+)
+
+target_sources(${TEST_NAME}
+    PRIVATE        
+        ${mbed-os_SOURCE_DIR}/events/source/equeue.c           
+        test_equeue.cpp
+)
+
+target_link_libraries(${TEST_NAME}
+    PRIVATE
+        mbed-headers
+        mbed-stubs-events
+        mbed-stubs-platform
+        gmock_main
+)
+
+add_test(NAME "${TEST_NAME}" COMMAND ${TEST_NAME})
+
+set_tests_properties(${TEST_NAME} PROPERTIES LABELS "equeue")