cbbackupmgr restore: support cross bucket mapping of scopes and collections

Krishna Doddi (Prasad) was trying to see if he would be able to restore a self-managed backup to a serverless database scope and realized that the cbbackupmgr restore --map-data option does not allow you to map scopes and collections to a different bucket.

cbbackupmgr restore --archive /home/couchbase/backups --repo couchmusic --cluster couchbases://cb.prasad-m1va8c.sdk.dev.nonprod-project-avengers.com --username N1nwmWmxxxxxxxxxxxxxxxxxxxxxxxx --password poaO5ZuWhOrOxxxxxxxxxxxxxxxxxxxxx --map-data couchmusic2.music.countries=prasad-m1va8c.couchmusic2.countries --no-ssl-verify

Error restoring cluster: invalid mapping 'couchmusic2.music.countries=prasad-m1va8c.couchmusic2.countries', scopes/collections can only be mapped inside the same bucket

Since the serverless database has a single bucket with a generated name that cannot be modified, the only option allowed for cbbackupmgr restore --map-data is to map at the bucket level, but if you want to just restore to a scope in the serverless database, you cannot do that.

Consider allowing restoring a scope or a collection to a different bucket.