option to specify format type in node plugin

[Madhu-1]

currently, external-provisioner defaults the format type to ext4, there is a discussion going on to provide an option in sidecar container kubernetes-csi/external-provisioner#328 .

if sidecar container does not provide an option to specify the format options, in ceph-csi we need to provide a flag to set it

[nixpanic]

@Madhu-1 this can be closed? We already support different filesystems, I think?

[Madhu-1]

yeah closing this one as we have option to specify the default filesystem in external-provisioner. Thanks for reminding me @nixpanic