Merge branch 'bugfix/nvs_leaks' into 'master'

nvs: fix memory leaks in HashList and nvs_close

Fixes TW8162.
Associated test case is run under Instruments on macOS, until I set up valgrind to test this automatically on Linux.

See merge request !150

components/nvs_flash/src/nvs_page.cpp

@@ -744,7 +744,7 @@ esp_err_t Page::erase()
     mFirstUsedEntry = INVALID_ENTRY;
     mNextFreeEntry = INVALID_ENTRY;
     mState = PageState::UNINITIALIZED;
-    mHashList = HashList();
+    mHashList.clear();
     return ESP_OK;
 }