cbbackupmgr: option to not restore tombstones (deleted documents)

When restoring to test environments, it is desired that tombstones not be restored (for resource savings).

Use case:

The customer is taking a backup of their production system and restoring to their test system.  There are a lot of tombstones, and it would save a lot of memory on their test system if they didn't restore the tombstones. 

Feature request:

1. Requesting an option for cbbackupmgr restore to not restore tombstones.  Suggested option names --disable-tombstones (P0)
2. Suggestion was also made for an option to skip restoring expired documents.  Currently, we have {}replace-ttl <type> with -replace-ttl-with <timestamp> to allow you to change the expiration time on a document (expiration time is an absolute Unix epoch time value), but we currently do not have an option to skip restoring expired documents (i.e. documents that have expiration time that is earlier than current Unix epoch time).  This should be a different option – suggested option name -disable-expired (P1)
3. Backup Service does not need to support these new options at this time.

Documentation should note:

--disable-tombstones:

The option may be useful when restoring production backups to test environments to allow resource savings.  To understand the role of a tombstone, see Tombstones.

--remove-expired:

The option may be used to not restore expired documents (documents that have expiration time that is earlier than the current Unix epoch time).  If you do wish to restore the expired documents, you can remove the expiration time or update the expiration time on a document using the {}replace-ttl <type>{-} and {{-replace-ttl-with <timestamp> }}options.   For more information on expiration settings, see Expiration.