API call to get a snapshot of running queries

### Version

3.4.0

### Feature

For debugging performance issues, it would be useful to be able to get a snapshot of the queries currently being processed, via an API call. It's possible to see all the queries that have been processed, by using logging, but sometimes you just want to get an instantaneous view, which is harder with the logging method.

If the API could return a list of the queries being processed, with: query text, current run time, and any out-of-band parameters (e.g. things passed as URL parameters), then I think that would be ideal. We've found a similar feature useful in GraphDB.

### Are you interested in contributing a solution yourself?

No

The issue names no files or tests; begin by locating the API entry point for query-processing state and reviewing how logging currently exposes processed queries. Done means an API call returns a snapshot of active queries including query text, current runtime, and out-of-band parameters.

Written by the indexing model from the issue text.