Collections: DCP stream-request for collection extra seqno checks required.

Note: This MB used to track a feature called anti-lag, away to stop DCP clients falling behind the purge-seqno - the comments write up an idea that means we can use the collection high-seqno to determine if a client behind the purge-seqno can still safely re-connect.

https://issues.couchbase.com/browse/MB-32358?focusedCommentId=421402&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-421402

The technique only need apply to DCP clients that choose a scope or collection and does not apply to 'replication'. When a scope or muliple collections are selected, the technique needs to consider all collections, only if all collections satisfy the condition can we proceed.