New './kubestr file-restore' command to copy files from Snapshot to PVC

[shlokc9]

Description

The ./kubestr browse commands allow us to browse through the contents of a PVC or VolumeSnapshot either using a Filebrowser GUI service or a CLI output. We can use this functionality to further implement a command that copies any file(s) from the contents of VolumeSnapshot to it's source PVC.

Proposed changes

> ./kubestr file-restore --fromSnapshot <snapshot-name> --toPVC <pvc-name> -n <namespace>

This command would mount both the VolumeSnapshot (i.e. the restored PVC from snapshot) and it's source PVC to the browse pod. And when the Filebrowser service is exposed on the CLI, the users can select file(s) on it's GUI to copy from restored PVC to source PVC .

> ./kubestr file-restore --fromSnapshot <snapshot-name> -n <namespace> --path <some-file-path>

The --path flag here would let the user mention a specific path on the restored PVC to pick file(s) from and copy the file(s) on the source PVC without using the Filebrowser service. Instead of Filebrowser GUI, we would simply run a cp POSIX command where both the source path and destination path would be expected via the --path flag.