feat(freertos): Added FreeRTOS POSIX/Linux Simulator

* Added port layer from the FreeRTOS POSIX port, added
  additional port code for ESP-IDF.
* Created another hello world example using that POSIX
  port in tools/test_apps.
* Removed old linux app

.gitlab/ci/host-test.yml

@@ -380,6 +380,15 @@ test_esp_event:
     - idf.py build
     - build/test_esp_event_host.elf
 
+test_hello_world_linux_compatible_example:
+  extends: .host_test_template
+  script:
+    - cd ${IDF_PATH}/tools/test_apps/linux_compatible/hello_world_linux_compatible
+    - idf.py --preview set-target linux
+    - idf.py build
+    - timeout 15 build/hello_world.elf > test.log
+    - grep "Hello world!" test.log
+
 test_esp_timer_cxx:
   extends: .host_test_template
   script:
@@ -429,14 +438,6 @@ test_system_cxx:
     - idf.py build
     - build/test_system_cxx_host.elf
 
-test_linux_example:
-  extends: .host_test_template
-  script:
-    - cd ${IDF_PATH}/examples/build_system/cmake/linux_host_app
-    - idf.py build
-    - timeout 5 ./build/linux_host_app.elf >test.log || true
-    - grep "Restarting" test.log
-
 test_partition_api_host:
   extends: .host_test_template
   script: