[MQTT] Simplifies MQTT CMakeLists file

- Uses mocks from tools instead of creating them.
- Move host based definition to test code.

tools/mocks/freertos/include/FreeRTOSConfig.h

@@ -0,0 +1,25 @@
+/*
+ * SPDX-FileCopyrightText: 2022 Espressif Systems (Shanghai) CO LTD
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+#define STACK_OVERHEAD_CHECKER                          256
+#define STACK_OVERHEAD_OPTIMIZATION                     320
+#define STACK_OVERHEAD_APPTRACE                         1280
+#define STACK_OVERHEAD_WATCHPOINT                       60
+#define configSTACK_OVERHEAD_TOTAL (                              \
+                                    STACK_OVERHEAD_CHECKER +      \
+                                    STACK_OVERHEAD_OPTIMIZATION + \
+                                    STACK_OVERHEAD_APPTRACE +     \
+                                    STACK_OVERHEAD_WATCHPOINT     \
+                                                            )
+#define configMINIMAL_STACK_SIZE                        ( 768 + configSTACK_OVERHEAD_TOTAL )
+#define configMAX_PRIORITIES                            ( 25 )  //This has impact on speed of search for highest priority
+#define configUSE_PREEMPTION                            1
+#define configUSE_IDLE_HOOK                             CONFIG_FREERTOS_USE_IDLE_HOOK
+#define configUSE_TICK_HOOK                             CONFIG_FREERTOS_USE_TICK_HOOK
+#define configUSE_16_BIT_TICKS                          0
+#define configUSE_TRACE_FACILITY 1
+#define configSUPPORT_DYNAMIC_ALLOCATION                1
+#define configUSE_MUTEXES                               1
+#define configUSE_RECURSIVE_MUTEXES                     1