feat(mdns): Support user defined allocators

Defines mem-alloc function optionally weak, so users can override them
and implement their own allocation, or a static/bss memory for the mdns
task stack.

components/mdns/tests/test_afl_fuzz_host/esp32_mock.c

@@ -126,16 +126,6 @@ uint32_t esp_log_timestamp(void)
     return 0;
 }
 
-void *heap_caps_malloc(size_t size, uint32_t caps)
-{
-    return malloc(size);
-}
-
-void heap_caps_free(void *ptr)
-{
-    free(ptr);
-}
-
 void *mdns_mem_malloc(size_t size)
 {
     return malloc(size);
@@ -160,3 +150,13 @@ char *mdns_mem_strndup(const char *s, size_t n)
 {
     return strndup(s, n);
 }
+
+void *mdns_mem_task_malloc(size_t size)
+{
+    return malloc(size);
+}
+
+void mdns_mem_task_free(void *ptr)
+{
+    free(ptr);
+}