Backport index gatekeeper (permits) to v1

[dennisvang]

Backport the index permit implementation from #454 (develop) onto v1.17.x

This is new functionality, so that implies a bump to v1.18.

Also see

• FDP Index gatekeeper #592
• FAIRDataTeam/jira-backlog-migration#32

[dennisvang]

fixed in #707