mgr/dashboard: validate args in nvmeof top cmds

mgr/dashboard: validate args in nvmeof top cmds

This commit makes these changes to nvmeof top tool:
1. Improve/cleanup help text
2. Rename args (--group, --server-addr, --subsystem) to
   (--gw-group, --server-address, --nqn) to match other nvmeof cmds
3. Validate args --period, --gw-group, --server-address, --sort-by
4. Remove --service arg (since group and service have 1-1 mapping, this is redundant)
5. Show all cpu stats if no args are passed to "ceph nvmeof top cpu"
6. Don't show busy/idle rate more than 100%

Fixes: https://tracker.ceph.com/issues/75927
Signed-off-by: Vallari Agrawal <vallari.agrawal@ibm.com>