rbd: Add support for rbd ROX PVC mounting

if the PVC access mode is ReadOnlyMany
or single node readonly, mounting the rbd
device path to the staging path as readonly
to avoid the write operation.

If the PVC acccess mode is readonly, mapping
rbd images as readonly.

Signed-off-by: Madhu Rajanna <madhupr007@gmail.com>

internal/csi-common/nodeserver-default.go

@@ -194,3 +194,13 @@ func ConstructMountOptions(mountOptions []string, volCap *csi.VolumeCapability)
 	}
 	return mountOptions
 }
+
+// MountOptionContains checks the opt is present in mountOptions
+func MountOptionContains(mountOptions []string, opt string) bool {
+	for _, mnt := range mountOptions {
+		if mnt == opt {
+			return true
+		}
+	}
+	return false
+}