Ability to pause/resume indexing with FTS

Ref: https://forums.couchbase.com/t/pause-fts-temporarily/21824

There's some documentation on it here: https://docs.couchbase.com/server/current/rest-api/rest-fts-indexing.html#index-management

POST /api/index/{indexName}/ingestControl/{op}

Pause index updates and maintenance (no more ingesting document mutations).
Permission Required: cluster.bucket[bucket_name].fts!manage
Role Required: FTS-Admin
Parameters

• indexName: required, string, URL path parameter
  The name of the index whose control values will be modified.

• op: required, string, URL path parameter
  Allowed values for op are "pause" or "resume".

POST /api/index/{indexName}/planFreezeControl/{op}

Freeze the assignment of index partitions to nodes.
Permission Required: cluster.bucket[bucket_name].fts!manage
Role Required: FTS-Admin
Parameters

• indexName: required, string, URL path parameter
  The name of the index whose control values will be modified.

• op: required, string, URL path parameter
  Allowed values for op are "freeze" or "unfreeze".

The above endpoints don't seem to work as advertised however. 

The expectation should be that it kills the DCP connections of the index on "pause" and upon "resume" the DCP connection are setup again to pick up things where they were last left.