Add more flexibilities to support finer grained selection in backup

[reasonerjt]

Describe the problem/challenge you have
Currently, a user can define filters in the Backup CR to include/excluce resources based on the resource names, i.e. he/she can choose to select all pods or services into the backup in certain namespaces, and choose whether or not to include all cluster level resources into the backup.

We should provide more flexible selector/filter in the backup to allow user to select resource without having to update the workload, like adding labels.

There are several issue opened:

Support cluster resource Includes/Excludes
Need a way to skip backup of volumes based on type
Persistent Volume backup policy in Velero
Add new field additionalResources in backup spec

Let's try to combine the effort and decide what changes will be made in v1.11