Implement 'SHOW QUERIES' for InfluxDB v2

__Proposal:__
Implement the 'SHOW QUERIES' and 'KILL QUERY' present in InfluxDB 1.x into InfluxDB 2.x

__Current behavior:__
Currently this feature does not exist in InfluxDB 2.x

__Desired behavior:__
For this feature to exist as it did in InfluxDB 1.x

__Alternatives considered:__
I did not find an alternative or workaround

__Use case:__
On InfluxDB 1.x we could run `SHOW QUERIES` to see what queries we had running. We used this sometimes to troubleshoot a high load and see a hanging query.

Now with InfluxDB 2 something happened that caused all cores to go to 100% however I cannot see what queries are currently running.It seems InfluxDB v2 does not support this.

I asked this on the [community forum](https://community.influxdata.com/t/what-is-the-influxdb-2-equivelant-of-show-queries/24954) and @Jayclifford345 responded to me that he believes this is currently not possible, and requested I submitted a feature request.

In my initial post I asked about the `SHOW QUERIES` option, but of course once we have identified a bad query we'd like to kill it as well, so having the `KILL QUERY` option available as well in InfluxDB 2.x would be great.

No implementation files or tests are named in the issue. Start by comparing the InfluxDB 1.x SHOW QUERIES and KILL QUERY behavior with the current InfluxDB 2.x query handling; done means both capabilities are available for identifying and stopping running queries.

Written by the indexing model from the issue text.