Filters by volume types

[Lyndon-Li]

See issue #6450, sometimes, users want to filter volumes by volume types(i.e., configMap volumes, emptyDir volumes) from various backup types (i.e., file system backup, volume/CSI snapshot).
Looks like there is no existing way for uses to do this easily, if so, we may need to add this in Velero filter mechanisms.

[reasonerjt]

We may consider add a new condition in the volume policy to let user optionally skip hostPath, emptyDir by checking the keys of entries in .spec.volumes of pods.

[qiuming-best]

Added one new field VolumeTypes string slice in volumeConditions struct

type volumeConditions struct {
	Capacity     string           `yaml:"capacity,omitempty"`
	StorageClass []string         `yaml:"storageClass,omitempty"`
	NFS          *nFSVolumeSource `yaml:"nfs,omitempty"`
	CSI          *csiVolumeSource `yaml:"csi,omitempty"`
	VolumeTypes  []string         `yaml:"volumeTypes,omitempty"`
}

below is an example showing that pod mounted PV with cinder or awsElasticBlockStore volume type should be selected and skipped to be backed up.

version: v1
volumePolicies:
- conditions:
    volumeTypes:
      - cinder
      - awsElasticBlockStore
  action:
    type: skip

below is one example of a backup of one pod with awsElasticBlockStore type of PV, and skipped being backed up.

time="2023-09-22T03:38:51Z" level=info msg="Summary for skipped PVs: [{\"name\":\"pvc-d3163b24-6b28-4a57-8419-c9bbb568fdd8\",\"reasons\":[{\"approach\":\"any\",\"reason\":\"skipped due to resource policy \"},{\"approach\":\"volumeSnapshot\",\"reason\":\"matched action is 'skip' in chosen resource policies\"}]}]" backup=velero/b6 logSource="pkg/backup/backup.go:434"