Show non-heap-memory-usage in server preview

The memory information in the server status preview currently only shows information about the attribute heap-memory-usage, but the resource also provides non-heap memory usage via the attribute non-heap-memory-usage.

This issue is about adding the attribute non-heap-memory-usage to the server status preview.

The server status preview of the console must contain an additional section about the non-heap memmory usage.

This new section must contains two values:

The unit for both values is MB.

Add a test to verify that both values are present in the server preview.

See the official HAL website at https://hal.github.io