Message sidebar shows index name only, but not index set

## What?

When viewing the details of a message, it can be relevant to have a look/edit the index set it is stored in. Unfortunately, message details only show the _name_ of the index the message is stored in. There should be a link to the index set as well.

## Why?

Sometimes it is desired to e.g. look up or modify retention settings for the underlying storage when viewing a message. Right now it is rather hard to get from a message to the index set storing it, because only the index name is shown and it would require to go the indices page and find the matching index set which has this prefix.

## Your Environment

* Graylog Version:
* OpenSearch Version:
* MongoDB Version:
* Operating System:
* Browser version: