src/pybind/mgr: Add nvmeof-top tool

Add src/pybind/mgr/dashboard/services/nvmeof_top_cli.py
which adds commands:
"ceph nvmeof top io <subsystem>"
"ceph nvmeof top cpu"

This file is moved from the original work in:
https://github.com/pcuzner/ceph-nvmeof-top

Fixes: https://tracker.ceph.com/issues/64578

Co-authored-by: Paul Cuzner <pcuzner@ibm.com>
Signed-off-by: Vallari Agrawal <vallari.agrawal@ibm.com>