feat(heap): Add walker to the heap component

Introduce new APIs in essp_heap_caps.h:
- heap_caps_walk()
- heap_caps_walk_all()

Those functions are triggering a callback for all blocks
(allocated or free) of memory present in heaps meeting
the set of capabilities passed as parameter (or all heaps
for heap_caps_walk_all() function)

test_walker.c added to test the new functionality in
test_apps/heap_test/

components/heap/include/multi_heap.h

@@ -1,5 +1,5 @@
 /*
- * SPDX-FileCopyrightText: 2015-2023 Espressif Systems (Shanghai) CO LTD
+ * SPDX-FileCopyrightText: 2015-2024 Espressif Systems (Shanghai) CO LTD
  *
  * SPDX-License-Identifier: Apache-2.0
  */
@@ -207,6 +207,26 @@ size_t multi_heap_reset_minimum_free_bytes(multi_heap_handle_t heap);
  */
 void multi_heap_restore_minimum_free_bytes(multi_heap_handle_t heap, const size_t new_minimum_free_bytes_value);
 
+/**
+ * @brief Callback called when walking the given heap blocks of memory
+ *
+ * @param block_ptr Pointer to the block data
+ * @param block_size The size of the block
+ * @param block_used Block status. 0 if free, else, false
+ * @param user_data Opaque pointer to user defined data
+ */
+typedef void (*multi_heap_walker_cb_t)(void *block_ptr, size_t block_size, int block_used, void *user_data);
+
+/**
+ * @brief Call the tlsf_walk_pool function of the heap given as parameter with
+ * the walker function passed as parameter
+ *
+ * @param heap The heap to traverse
+ * @param walker_func The walker to trigger on each block of the heap
+ * @param user_data Opaque pointer to user defined data
+ */
+void multi_heap_walk(multi_heap_handle_t heap, multi_heap_walker_cb_t walker_func, void *user_data);
+
 #ifdef __cplusplus
 }
 #endif