vstart: Support deployment of ganesha daemon by cephadm with NFS option.

vstart: Support deployment of ganesha daemon by cephadm with NFS option.

NFS Ganesha cluster can be created in two ways with vstart
cluster:

1) With test_orchestrator
NFS=1 ../src/vstart.sh
This type of deployment can have multiple ganesha daemons on random port.

2) With Cephadm
NFS=1 ../src/vstart.sh --cephadm
It can deploy only single ganesha daemon with vstart on default ganesha port.

Both can create multiple cephfs exports.

Fixes: https://tracker.ceph.com/issues/45830
Signed-off-by: Varsha Rao <varao@redhat.com>