app/testpmd: add commands for TM capability and stats

app/testpmd: add commands for TM capability and stats

Add following CLIs to testpmd application for device traffic management;
- commands to display TM capability information.
  (per port, per hierarchy level and per hierarchy node)
- command to display hiearchy node type
- stats collection

Signed-off-by: Jasvinder Singh <jasvinder.singh@intel.com>
Tested-by: Yulong Pei <yulong.pei@intel.com>
Reviewed-by: Jingjing Wu <jingjing.wu@intel.com>
Acked-by: Cristian Dumitrescu <cristian.dumitrescu@intel.com>