freertos(IDF): Refactor port heap functions

Vanilla FreeRTOS expects applications to use one of the heap implementations
provided by FreeRTOS (i.e., heap_x.c), where functions such as pvPortMalloc()
and vPortFree() are defined in the heap implementation.

However, ESP-IDF already provides its own heap implementation
(i.e., esp_heap_caps.h). Thus, the pvPortMallc()/vPortFree() functions were
previously overriden by macro to call esp_heap functions directly.

This commit refactors the FreeRTOS port's heap as such:

- Added a heap_idf.c that implements all of the heap related functions required
  by FreeRTOS source
- All dynamic memory allocated by FreeRTOS is from internal memory. Thus, the
  FreeRTOS heap is the internal memory subset of the ESP-IDF heap.
- Removed some old macros to reduce diff from upstream source code.

components/freertos/FreeRTOS-Kernel/portable/linux/include/freertos/portmacro_idf.h

@@ -51,18 +51,30 @@ static inline BaseType_t IRAM_ATTR xPortGetCoreID(void)
     return (BaseType_t) 0;
 }
 
-static inline bool portVALID_TCB_MEM(const void *ptr)
-{
-    return true;
-}
+/**
+ * @brief Checks if a given piece of memory can be used to store a task's TCB
+ *
+ * - Defined in heap_idf.c
+ *
+ * @param ptr Pointer to memory
+ * @return true Memory can be used to store a TCB
+ * @return false Otherwise
+ */
+bool xPortCheckValidTCBMem(const void *ptr);
 
-static inline bool portVALID_STACK_MEM(const void *ptr)
-{
-    return true;
-}
+/**
+ * @brief Checks if a given piece of memory can be used to store a task's stack
+ *
+ * - Defined in heap_idf.c
+ *
+ * @param ptr Pointer to memory
+ * @return true Memory can be used to store a task stack
+ * @return false Otherwise
+ */
+bool xPortcheckValidStackMem(const void *ptr);
 
-#define pvPortMallocTcbMem(size)        pvPortMalloc(size)
-#define pvPortMallocStackMem(size)      pvPortMalloc(size)
+#define portVALID_TCB_MEM(ptr)      xPortCheckValidTCBMem(ptr)
+#define portVALID_STACK_MEM(ptr)    xPortcheckValidStackMem(ptr)
 
 BaseType_t xPortCheckIfInISR(void);