FIT Management: Implement Scoped Search Index Management

Same here for the missing comment. Vector Search and SearchV2 was added to the performer under but normal cluster/scope Search Index Management were missing, so the Cluster part of it was done last sprint, and I split the Scope part in this ticket since I was running out of time. But the additions are minor for this one, it did find a bug in the SDK however.

(Side-note, Jira is getting so buggy.  I can see in my emails and in the History tab that left a comment on this ticket - but I can't see it, and I can't see any note of a deletion in the History tab either.)

On looking at the PRs I realise that at least the SDK does have scoped index management, it's missing in the performer only.  The performer work was also meant to be done under / as part of the definition of done is passing the FIT tests, but it is reasonable that this ticket be branded as FIT-related.

N.b. this isn't really anything to do with FIT - this work was meant to be done under / ...